You are given two strings a and b consisting of lowercase English letters, both of length n. The characters of both strings have indices from 1 to n, inclusive. 

You are allowed to do the following changes: 

  * Choose any index i (1 ≤ i ≤ n) and swap characters a_i and b_i; 
  * Choose any index i (1 ≤ i ≤ n) and swap characters a_i and a_{n - i + 1}; 
  * Choose any index i (1 ≤ i ≤ n) and swap characters b_i and b_{n - i + 1}. 



Note that if n is odd, you are formally allowed to swap a_{⌈n/2⌉} with a_{⌈n/2⌉} (and the same with the string b) but this move is useless. Also you can swap two equal characters but this operation is useless as well.

You have to make these strings equal by applying any number of changes described above, in any order. But it is obvious that it may be impossible to make two strings equal by these swaps.

In one preprocess move you can replace a character in a with another character. In other words, in a single preprocess move you can choose any index i (1 ≤ i ≤ n), any character c and set a_i := c.

Your task is to find the minimum number of preprocess moves to apply in such a way that after them you can make strings a and b equal by applying some number of changes described in the list above.

Note that the number of changes you make after the preprocess moves does not matter. Also note that you cannot apply preprocess moves to the string b or make any preprocess moves after the first change is made.

Input

The first line of the input contains one integer n (1 ≤ n ≤ 10^5) — the length of strings a and b.

The second line contains the string a consisting of exactly n lowercase English letters.

The third line contains the string b consisting of exactly n lowercase English letters.

Output

Print a single integer — the minimum number of preprocess moves to apply before changes, so that it is possible to make the string a equal to string b with a sequence of changes from the list above.

Examples

Input

7
abacaba
bacabaa


Output

4


Input

5
zcabd
dbacz


Output

0

Note

In the first example preprocess moves are as follows: a_1 := 'b', a_3 := 'c', a_4 := 'a' and a_5:='b'. Afterwards, a = "bbcabba". Then we can obtain equal strings by the following sequence of changes: swap(a_2, b_2) and swap(a_2, a_6). There is no way to use fewer than 4 preprocess moves before a sequence of changes to make string equal, so the answer in this example is 4.

In the second example no preprocess moves are required. We can use the following sequence of changes to make a and b equal: swap(b_1, b_5), swap(a_2, a_4).
			     
			import java.io.*;
			        		    import java.math.*;
			        		    import java.util.*;
		import java.util.regex.Pattern;
		
		import javafx.scene.shape.Line;
			    	     
			        		    public class Main{
			        		  	private static InputStream stream;
			        		    	private static byte[] buf = new byte[1024];
			        		    	private static int curChar;
			        		    	private static int numChars;
			        		    	private static SpaceCharFilter filter;
			        		    	private static PrintWriter pw;
			        		    	private static long count = 0,mod=(long)1e9+7;
			        		    //	private static TreeSet<Integer> ts=new TreeSet[200000];
			public final static int INF = (int) 1E9;
			
			public static void main(String args[]) {
		    	
				InputReader(System.in);
				pw = new PrintWriter(System.out); 
			    new Thread(null ,new Runnable(){
			       public void run(){
			           try{
			        		
			               test();
		
			               pw.close();
			           } catch(Exception e){
			               e.printStackTrace();
			           }
			       }
			   },"1",1<<26).start();
			   	   }
			    static StringBuilder sb;
			    public static void test() throws IOException{
			    	 sb=new StringBuilder();
			    	
			    	 int t=1;
			    	 
			    	 while(t-->0){
			    		
			    		solve();
			    		//pw.println();
			    		//sb.append("\n");
			    	}
			    	//pw.println(sb);
			    }
			    
			    public static long pow(long n, long p,long mod) {
					if(p==0)
						return 1;
					if(p==1)
						return n%mod;
					if(p%2==0){
						long temp=pow(n, p/2,mod);
					return (temp*temp)%mod;
					}else{
						 	long temp=pow(n,p/2,mod);
						 	temp=(temp*temp)%mod;
						 	return(temp*n)%mod;
						 	
					}
				}
			    public static long pow(long n, long p) {
					if(p==0)
						return 1;
					if(p==1)
						return n;
					if(p%2==0){
						long temp=pow(n, p/2);
					return (temp*temp);
					}else{
						 	long temp=pow(n,p/2);
						 	temp=(temp*temp);
						 	return(temp*n);
						 	
					}
				}
			    public static void Merge(long a[],int p,int r){
			        if(p<r){
			            int q = (p+r)/2;
			            Merge(a,p,q);
			            Merge(a,q+1,r);
			            Merge_Array(a,p,q,r);
			        }
			    }
			    public static void Merge_Array(long a[],int p,int q,int r){
			       long b[] = new long[q-p+1];
			        long c[] = new long[r-q];
			        for(int i=0;i<b.length;i++)
			            b[i] = a[p+i];
			        for(int i=0;i<c.length;i++)
			            c[i] = a[q+i+1];
			        int i = 0,j = 0;
			        for(int k=p;k<=r;k++){
			            if(i==b.length){
			                a[k] = c[j];
			                j++;
			            }
			            else if(j==c.length){
			                a[k] = b[i];
			                i++;
			            }
			            else if(b[i]<c[j]){
			                a[k] = b[i];
			                i++;
			            }
			            else{
			                a[k] = c[j];
			                j++;
			            }
			        }
			    }
			    
			  
				public static long gcd(long x, long y) {
					if (x == 0)
						return y;
					else
						return gcd( y % x,x);
				}	
				
				public static boolean isPrime(int n) {
					if (n <= 1)
						return false;
					if (n <= 3)
						return true;
			 
					if (n % 2 == 0 || n % 3 == 0)
						return false;
			 
					for (int i = 5; i * i <= n; i = i + 6)
						if (n % i == 0 || n % (i + 2) == 0)
							return false;
			 
					return true;
				}
				
			        static LinkedList<Integer> adj[],adj2[];
			        static boolean Visited[];
			        static HashSet<Integer> exc;
			        static long oddsum[]=new long[1000001];
			        static long co=0;
			        static int indeg[],outdeg[];
	  		      
			    
			    	private static void buildgraph(int n){
			    		adj=new LinkedList[n+1];
			    		adj2=new LinkedList[n+1];
			    		Visited=new boolean[n+1];
			    		levl=new int[n+1];
			    		indeg=new int[n+1];
			    		outdeg=new int[n+1];
			    		for(int i=0;i<=n;i++){
			    			adj[i]=new LinkedList<Integer>();
			    			adj2[i]=new LinkedList<Integer>();
			    		}
			
			
			    	}
			      
			       
			        static int[] levl;
			        static int[] eat;
			        static int n,m;
			        static int price[];
			        //ind frog crab
			    
			        
			        static long d,x,y;
					static long modInverse(long A, long M)
					{
					extendedEuclid(A,M);
					return (x%M+M)%M;    //x may be negative
					}
					static void extendedEuclid(long A, long B) {
					if(B == 0) {
					d = A;
					x = 1;
					y = 0;
					}
					else {
					extendedEuclid(B, A%B);
					long temp = x;
					x = y;
					y = temp - (A/B)*y;
					}
					}
			        static double distance(int x1,int y1,int x2,int y2){
			        	return Math.sqrt((x1-x2)*(x1-x2) + (y1-y2)*(y1-y2));
			        }
			        static double area(int x1, int y1, int x2, int y2, int x3, int y3)
			        {
			           return Math.abs((x1*(y2-y3) + x2*(y3-y1)+ x3*(y1-y2))/2.0);
			        }
			        static boolean isInside(int x1, int y1, int x2, int y2, int x3, int y3, int x, int y)
			        {   
			           double A = area (x1, y1, x2, y2, x3, y3);
			         
			           double A1 = area (x, y, x2, y2, x3, y3);
			         
			           double A2 = area (x1, y1, x, y, x3, y3);
			         
			           double A3 = area (x1, y1, x2, y2, x, y);
			           
			          return (A == A1 + A2 + A3);
			        }
			      
					static int col[];
			    public static boolean isVowel(char c){
			    	if(c=='a' || c=='e'||c=='i' || c=='o' || c=='u')
			    		return true;
			    	return false;
			    }
			static long arr[], lazy[],ans[];
			static int c[],nodes[];
			static int dp[][];
			static long a[][];
			
			private static boolean isPrim(long n,int p){
				for (long i = 2; i * i <= n; i++) {
			        if (n % i == 0 && i <= p) return false;
			    }
			    return true;
			}
			//price - starting index of string with given hash
			//rating-count of number of time of a hash
			static ArrayList<String> all_perm;
			static boolean[][] visited1;
			static  boolean won;
			static boolean containsCycle;
			static ArrayList<Integer> anss;
			static int index = 0;
			static int trav[],subtree[];
		public static void solve() throws IOException{
	
			int n=nextInt();
			String a = nextLine();
			String b = nextLine();
			long ans=0;
			for (int i = 0; i < Math.ceil(n / 2.0); i++)
			{
				if (i == n - i - 1)
				{
					if (a.charAt(i) != b.charAt(i)){
						ans++;
					} 
					continue;
				}

				int c = 0;

				if (a.charAt(i) == b.charAt(i))
				{
					if (a.charAt(n-i-1) == b.charAt(n-i-1))
					{
						c = 0;
					} else
					{
						c++;
					}
				} else if (a.charAt(i) == b.charAt(n-i-1))
				{
					if (a.charAt(n-i-1) == b.charAt(i))
					{

					} else
					{
						c++;
					}

				} else
				{
					c++;

					if (a.charAt(n-i-1) != b.charAt(i) && a.charAt(n-i-1)!=b.charAt(n-i-1))
					{
						c++;
					}
				}

				if (a.charAt(n-i-1) == a.charAt(i) && b.charAt(i) == b.charAt(n-i-1))
				{
					c = 0;
				} else if (b.charAt(n-i-1) == b.charAt(i))
				{
					c = 1;
				}
				ans += c;
			}
			pw.println(ans);

		}
		
		static int res=0;
		private static void dfs(int start, int par){
			Visited[start] = true;
			trav[index] = start;
			index++;
			for(int x: adj[start]){
				if(!Visited[x]){
					dfs(x, start);
				}
			}
			subtree[start]++;
			subtree[par]+=subtree[start];
		}
		private static boolean isPalindrome(int freq[]){
			int odd=0;
			for(int i=0;i<26;i++){
				if(freq[i]%2!=0){
					odd++;
				}
			}
			if(odd<=1)
				return true;
			return false;
		}
			
			private static int mySoln(int n,int a,int b){
				int tempa=Math.min(a, b);
				int tempb=Math.max(a, b);
				ArrayList<Integer> list = new ArrayList<Integer>();
				for(int i=1;i<=n;i++){
					list.add(i);
				}
				
				int round=1;
				while(true){
					ArrayList<Integer> temp = new ArrayList<Integer>();
					
					for(int i=0;i<list.size();i+=2){
						if(list.get(i)==tempa && list.get(i+1)==tempb){
							
							return round;
						}
						if(list.get(i)==tempa ||  list.get(i)==tempb){
							temp.add(list.get(i));
						}else if(list.get(i+1)==tempa || list.get(i+1)==tempb){
							temp.add(list.get(i+1));
						}else{
							temp.add(list.get(i));
						}
					}
					
					list.clear();
					for(int i:temp){
						list.add(i);
					}
				
					round++;
				
					
				}
			}
			private static int othersoln(int n,int a,int b){
			for(int i=16;i>=0;i--){
				if(BB(a,i) ^ BB(b,i)){
					int m=i+1;
					
						return m;
								
			}
			}
			return 0;
			
			}
			private static boolean BB(int n,int i){
				return (n & (1<<i)) >0;
			}
					private static boolean check(int x,int y,int n,int m){
				if(x>=0 && x<n && y>=0 && y<m)
					return true;
				return false;
			}
					
					
					
								
			
			    private static boolean Check(int x,int y,int n){
					if(x>=0 && x<n && y>=0 && y<n)
						return true;
					return false;
				}
			    
			    public static String reverseString(String s) {
					StringBuilder sb = new StringBuilder(s);
					sb.reverse();
					return (sb.toString());
				}
			    
			  /*  
			   private static void BFS(int sou){
			    	Queue<Integer> q=new LinkedList<Integer>();
			    	q.add(sou);
			    	Visited[sou]=true;
			    	levl[sou]=0;
			    	while(!q.isEmpty()){
			    		int top=q.poll();
			    		
			    		for(int i:adj[top]){
			    			//pw.println(i+" "+top);
						if(!Visited[i])
						{
							
							q.add(i);
							levl[i]=levl[top]+1;
						}
						
						Visited[i]=true;
						
						}
					}
				}*/
				
			
			
			
			    		      
			    		   /* private static void kahn(int n){
			    		    	
			    		    	PriorityQueue<Integer> q=new PriorityQueue<Integer>();
			    				for(int i=1;i<=n;i++){
			    					if(indeg[i]==0){
			    						q.add(i);
			    					}
			    				}
			    				while(!q.isEmpty()){
			    					int top=q.poll();
			    					st.push(top);
			    					for(Node i:adj[top]){
			    						indeg[i.to]--;
			    						if(indeg[i.to]==0){
			    							q.add(i.to);
			    						}
			    					}
			    				}
			    		    }
			    		        
			    		        static int state=1;
			    		        static long no_exc=0,no_vert=0;
			    		      static Stack<Integer> st;
			    		      static HashSet<Integer> inset;
			    		     /*   private static void topo(int curr){
			    		        	
			    		        	Visited[curr]=true;
			    		        	inset.add(curr);
			    		        	for(int x:adj[curr]){
			    		        		if(adj[x].contains(curr) || inset.contains(x)){
			    		        			state=0;
			    		        			return;
			    		        		}
			    		        		if(state==0)
			    		        			return;
			    		        		
			    		        	}
			    		        	st.push(curr);
			    		        	
			    		        	inset.remove(curr);
			    		        }*/
			    		        static HashSet<Integer> hs;
			    		       
			    		     
			    		     	static boolean prime[];
								static int spf[];
								public static void sieve(int n){
									prime=new boolean[n+1];
									spf=new int[n+1];
									
									Arrays.fill(spf, 1);
									Arrays.fill(prime, true);
								prime[1]=false;
									spf[2]=2;
									
								for(int i=4;i<=n;i+=2){
									spf[i]=2;
								}
								for(int i=3;i<=n;i+=2){
									if(prime[i]){
										spf[i]=i;
										for(int j=2*i;j<=n;j+=i){
											
											prime[j]=false;
										if(spf[j]==1){
											spf[j]=i;
										}
										}
									}
								}
								
									
								}
			    		     	
			    		    	// To Get Input
			// Some Buffer Methods
			 
			    		     	public static void sort(long a[]){
			    		     		Merge(a, 0, a.length-1);
			    		     	}
			    		    	public static void InputReader(InputStream stream1) {
			    		    		stream = stream1;
			    		    	}
			 
			    		    	private static boolean isWhitespace(int c) {
			    		    		return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
			    		    	}
			 
			    		    	private static boolean isEndOfLine(int c) {
			    		    		return c == '\n' || c == '\r' || c == -1;
			    		    	}
			 
			    		    	private static int read() {
			    		    		if (numChars == -1)
			    		    			throw new InputMismatchException();
			    		    		if (curChar >= numChars) {
			    		    			curChar = 0;
			    		    			try {
			    		    				numChars = stream.read(buf);
			    		    			} catch (IOException e) {
			    		    				throw new InputMismatchException();
			    		    			}
			    		    			if (numChars <= 0)
			    		    				return -1;
			    		    		}
			    		    		return buf[curChar++];
			    		    	}
			 
			    		    	private static int nextInt() {
			    		    		int c = read();
			    		    		while (isSpaceChar(c))
			    		    			c = read();
			    		    		int sgn = 1;
			    		    		if (c == '-') {
					sgn = -1;
					c = read();
				}
				int res = 0;
				do {
					if (c < '0' || c > '9')
						throw new InputMismatchException();
					res *= 10;
					res += c - '0';
			    		    			c = read();
			    		    		} while (!isSpaceChar(c));
			    		    		return res * sgn;
			    		    	}
			 
			    		    	private static long nextLong() {
			    		    		int c = read();
			    		    		while (isSpaceChar(c))
			    		    			c = read();
			    		    		int sgn = 1;
			    		    		if (c == '-') {
					sgn = -1;
					c = read();
				}
				long res = 0;
				do {
					if (c < '0' || c > '9')
						throw new InputMismatchException();
					res *= 10;
					res += c - '0';
			    		    			c = read();
			    		    		} while (!isSpaceChar(c));
			    		    		return res * sgn;
			    		    	}
			 
			    		    	private static String nextToken() {
			    		    		int c = read();
			    		    		while (isSpaceChar(c))
			    		    			c = read();
			    		    		StringBuilder res = new StringBuilder();
			    		    		do {
			    		    			res.appendCodePoint(c);
			    		    			c = read();
			    		    		} while (!isSpaceChar(c));
			    		    		return res.toString();
			    		    	}
			 
			    		    	private static String nextLine() {
			    		    		int c = read();
			    		    		while (isSpaceChar(c))
			    		    			c = read();
			    		    		StringBuilder res = new StringBuilder();
			    		    		do {
			    		    			res.appendCodePoint(c);
			    		    			c = read();
			    		    		} while (!isEndOfLine(c));
			    		    		return res.toString();
			    		    	}
			 
			    		    	private static int[] nextIntArray(int n) {
			    		    		int[] arr = new int[n];
			    		    		for (int i = 0; i < n; i++) {
			    		    			arr[i] = nextInt();
			    		    		}
			    		    		return arr;
			    		    	}
			 
			    		    	private static long[][] next2dArray(int n, int m) {
			    		    		long[][] arr = new long[n][m];
			    		    		for (int i = 0; i < n; i++) {
			    		    			for (int j = 0; j < m; j++) {
			    		    				arr[i][j] = nextLong();
			    		    			}
			    		    		}
			    		    		return arr;
			    		    	}
			    		    	private static char[][] nextCharArray(int n,int m){
			    		    		char [][]c=new char[n][m];
			    		    		for(int i=0;i<n;i++){
			    		    			String s=nextLine();
			    		    			for(int j=0;j<s.length();j++){
			    		    				c[i][j]=s.charAt(j);
			    		    			}
			    		    		}
			    		    		return c;
			    		    	}
			 
			    		    	private static long[] nextLongArray(int n) {
			    		    		long[] arr = new long[n];
			    		    		for (int i = 0; i < n; i++) {
			    		    			arr[i] = nextLong();
			    		    		}
			    		    		return arr;
			    		    	}
			 
			    		    	private static void pArray(int[] arr) {
			    		    		for (int i = 0; i < arr.length; i++) {
			    		    			pw.print(arr[i] + " ");
			    		    		}
			    		    		pw.println();
			    		    		return;
			    		    	}
			 
			    		    	private static void pArray(long[] arr) {
			    		    		for (int i = 0; i < arr.length; i++) {
			    		    			pw.print(arr[i] + " ");
			    		    		}
			    		    		pw.println();
			    		    		return;
			    		    	}
			 
			    		    	private static void pArray(boolean[] arr) {
			    		    		for (int i = 0; i < arr.length; i++) {
			    		    			pw.print(arr[i] + " ");
			    		    		}
			    		    		pw.println();
			    		    		return;
			    		    	}
			 
			    		    	private static boolean isSpaceChar(int c) {
			    		    		if (filter != null)
			    		    			return filter.isSpaceChar(c);
			    		    		return isWhitespace(c);
			    		    	}
			 
			    		    	private interface SpaceCharFilter {
			    		    		public boolean isSpaceChar(int ch);
			    		    	}
			    		    	
			
			}
			    		    
			    		        class Node{
			    		    	int to;
			    		    	long dist;
			    		    	Node(int to,long dist){
			    		    		this.to=to;
			    		    		this.dist=dist;
			    		    	}
			    		    	
			    		    }
			    		        class Qu{
			    		    		long a0,a1,a2,a3;
			    		    		public Qu(long a0,long a1,long a2,long a3) {
			    		    			this.a0=a0;
			    		    			this.a1=a1;
			    		    			this.a2=a2;
			    		    			this.a3=a3;
			    		    		}
			    		    }
			    		
			class Dsu{
			private int rank[], parent[] ,n;
			long str[],si[],larg[];
			long max=0;
			int cnt=0;
			private static int[] parent1;
			Dsu(int size){
				this.n=size+1;
				rank=new int[n];
				cnt=n-1;
				//parent=new int[n];
			    		    		    		parent=new int[n];
			    		    		    		str=new long[n];
			    		    		    		si=new long[n];
			    		    		
			    		    		    		larg=new long[n];
			    		    		    		makeSet();
			    		    		
			    		    		    	}
			    		    		    	
			    		    		    	void makeSet(){
			    		    		    		for(int i=0;i<n;i++){
			    		    		    			parent[i]=i;
			    		    		    			si[i]=1;
			    		    		    		}
			    		    		    	}
			    		    		    	
			    		    		    	int find(int x){
			    		    		    		if(parent[x]!=x){
			    		    		    			
			    		    		    			parent[x]=find(parent[x]);
			    		    		    		}
			    		    		    		return parent[x];
			    		    		    	}
			    		    		    	
			    		    		    	void join(int ind,long val){
			    		    		    		if(str[ind]==0){
			    		    		    			str[ind]=val;
			    		    		    			larg[ind]=val;
			    		    		    			max=Math.max(max, str[ind]);
			    		    		    		}
			    		    		    		int prev_ind=(ind-1);
			    		    		    		int next_ind=(ind+1);
			    		    		    		if(prev_ind>0 && larg[prev_ind]!=0){
			    		    		    			union(prev_ind,ind);
			    		    		    		}
			    		    		    		if(next_ind<n && larg[next_ind]!=0){
			    		    		    			union(next_ind,ind);
			    		    		    		}
			    		    		    		
			    		    		    	}
			    		    		    
			    		    		    	
			    		    		    	boolean union(int x,int y){
			    		    		    		int xRoot=find(x);
			    		    		    		int yRoot=find(y);
			    		    		    
			    		    		    	
			    		    		    		if(xRoot==yRoot)
			    		    		    			return false;
			    		    		    		if(rank[xRoot]<rank[yRoot]){
			    		    		    		parent[xRoot]=yRoot;
			    		    		    		
			    		    		    		larg[yRoot]=Math.max(larg[xRoot], larg[yRoot]);
			    		    		    		
			    		    		    		si[yRoot]+=si[xRoot];
			    		    		    		str[yRoot]=larg[yRoot]*si[yRoot];
			    		    		    			max=Math.max(str[yRoot], max);
			    		    		    		}else if(rank[yRoot]<rank[xRoot]){
			    		    		    			parent[yRoot]=xRoot;
			     
			    		    		    			larg[xRoot]=Math.max(larg[xRoot], larg[yRoot]);
			        		    		    		
			        		    		    		si[xRoot]+=si[yRoot];
			        		    		    		str[xRoot]=larg[xRoot]*si[xRoot];
			    			    		    		max=Math.max(str[xRoot], max);
			    		    		    		}else{
			    		    		    			parent[yRoot]=xRoot;
			    		    		    			rank[xRoot]++;
			     
			    		    		    			larg[xRoot]=Math.max(larg[xRoot], larg[yRoot]);
			        		    		    		
			        		    		    		si[xRoot]+=si[yRoot];
			        		    		    		str[xRoot]=larg[xRoot]*si[xRoot];
			    			    		    		max=Math.max(str[xRoot], max);
			    		    		    		
			    		    		    		}
			    		    		    		cnt--;
			    		    		    		return true;
			    		    		    	}
			    	
			    		    		     
			    		    		    }
		class Pair1 implements Comparable<Pair1>{
				long price,rating;
				Pair1(long a,long b){
					this.price=a;
					this.rating=b;
				}
				@Override
				public int compareTo(Pair1 arg0) {
					
						return (int)(-1*((arg0.rating - arg0.price)-(rating-price)));
					
				}
			
			
			}
			  
			
