You are given a grid, consisting of 2 rows and n columns. Each cell of this grid should be colored either black or white.

Two cells are considered neighbours if they have a common border and share the same color. Two cells A and B belong to the same component if they are neighbours, or if there is a neighbour of A that belongs to the same component with B.

Let's call some bicoloring beautiful if it has exactly k components.

Count the number of beautiful bicolorings. The number can be big enough, so print the answer modulo 998244353.

Input

The only line contains two integers n and k (1 ≤ n ≤ 1000, 1 ≤ k ≤ 2n) — the number of columns in a grid and the number of components required.

Output

Print a single integer — the number of beautiful bicolorings modulo 998244353.

Examples

Input

3 4


Output

12


Input

4 1


Output

2


Input

1 2


Output

2

Note

One of possible bicolorings in sample 1:

<image>
import java.io.*;
import java.util.*;
import java.text.*;
import java.lang.*;
import java.lang.reflect.Array;
import java.math.BigInteger;
import java.util.regex.*;
public class Main {
       //  public static ArrayList a[]=new ArrayList[300001];
       /* static long[] seg=new long[4000000];
        static void build(int node,int start,int end) {
        	if(start==end) {
        		seg[node]=0;
        		return ;
        	}
        	int mid=(start+end)/2;
        	build(2*node+1,start,mid);
        	build(2*node+2,mid+1,end);
        	seg[node]=seg[2*node+1]+seg[2*node+2];
        }
       static void update(int node,int start,int end,int idx) {
    	   if(start==end) {
    		   seg[node]=1;
    		   return ;
    	   }
    	   int mid=(start+end)/2;
    	   if(idx>=start && idx<=mid) {
    		   update(2*node+1,start,mid,idx);
    	   }
    	   else
    		   update(2*node+2,mid+1,end,idx);
    	   seg[node]=seg[2*node+1]+seg[2*node+2];
       }
       static long query(int node,int start,int end,int l,int r) {
        
    	   if(r<start || end<l)
    		   return 0;
    	   if(start>=l && end<=r)
    		   return seg[node];
    	   int mid=(start+end)/2;
    	   return (query(2*node+1,start,mid,l,r)+query(2*node+2,mid+1,end,l,r));
       }*/
		public static void main(String[] args) 
        {
            InputReader in = new InputReader(System.in);
            PrintWriter pw = new PrintWriter(System.out);
            long dp[][][]=new long[1001][2001][4];
            int n=in.nextInt();
            int k=in.nextInt();
            mod=998244353;
            dp[1][1][0]=1L;
            dp[1][1][3]=1L;
            dp[1][2][1]=1L;
            dp[1][2][2]=1L;
            for(int i=2;i<1001;i++) {
            	for(int j=1;j<=2000;j++) {
            		dp[i][j][0]=(dp[i][j][0]+dp[i-1][j][0])%mod;
            		dp[i][j][0]=(dp[i][j][0]+dp[i-1][j-1][3])%mod;
            		dp[i][j][0]=(dp[i][j][0]+dp[i-1][j][1])%mod;
            		dp[i][j][0]=(dp[i][j][0]+dp[i-1][j][2])%mod;
            		
            		dp[i][j][1]=(dp[i][j][1]+dp[i-1][j-1][0])%mod;
            		dp[i][j][1]=(dp[i][j][1]+dp[i-1][j-1][3])%mod;
            		dp[i][j][1]=(dp[i][j][1]+dp[i-1][j][1])%mod;
            		dp[i][j][1]=(dp[i][j][1]+(j-2>=0?dp[i-1][j-2][2]:0)%mod);
            		
            		dp[i][j][2]=(dp[i][j][2]+dp[i-1][j-1][0])%mod;
            		dp[i][j][2]=(dp[i][j][2]+dp[i-1][j-1][3])%mod;
            		dp[i][j][2]=(dp[i][j][2]+dp[i-1][j][2])%mod;
            		dp[i][j][2]=(dp[i][j][2]+(j-2>=0?dp[i-1][j-2][1]:0)%mod);
            		
            		dp[i][j][3]=(dp[i][j][3]+dp[i-1][j-1][0])%mod;
            		dp[i][j][3]=(dp[i][j][3]+dp[i-1][j][3])%mod;
            		dp[i][j][3]=(dp[i][j][3]+dp[i-1][j][1])%mod;
            		dp[i][j][3]=(dp[i][j][3]+dp[i-1][j][2])%mod;
            		
            	}
            }
            long ans=0L;
            for(int i=0;i<4;i++) {
            	ans=(ans+dp[n][k][i])%mod;
            }
            pw.println(ans);
            pw.flush();
            pw.close();
        
        }
		private static void debug(Object... o) {
			System.out.println(Arrays.deepToString(o));
		}
        static class InputReader 
        {
        private final InputStream stream;
        private final byte[] buf = new byte[8192];
        private int curChar, snumChars;
        private SpaceCharFilter filter;
 
        public InputReader(InputStream stream) 
        {
            this.stream = stream;
        }
        public int snext() 
        {
            if (snumChars == -1)
                throw new InputMismatchException();
            if (curChar >= snumChars) 
            {
                curChar = 0;
                try 
                {
                    snumChars = stream.read(buf);
                } 
                
                catch (IOException e) 
                {
                    throw new InputMismatchException();
                }
                
                if (snumChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }
 
        public int nextInt() 
        {
            int c = snext();
            while (isSpaceChar(c)) 
            {
                c = snext();
            }
            int sgn = 1;
            if (c == '-')
            {
                sgn = -1;
                c = snext();
            }
            int res = 0;
            do 
            {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = snext();
            } while (!isSpaceChar(c));
            return res * sgn;
        }
 
        public long nextLong()
        {
            int c = snext();
            while (isSpaceChar(c)) 
            {
                c = snext();
            }
            int sgn = 1;
            if (c == '-') 
            {
                sgn = -1;
                c = snext();
            }
            long res = 0;
            do 
            {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = snext();
            } while (!isSpaceChar(c));
            return res * sgn;
        }
 
        public int[] nextIntArray(int n) 
        {
            int a[] = new int[n];
            for (int i = 0; i < n; i++) 
            {
                a[i] = nextInt();
            }
            return a;
        }
        static class tri implements Comparable<tri> {
            int p, c, l;
 
            tri(int p, int c, int l) {
                this.p = p;
                this.c = c;
                this.l = l;
            }
 
            public int compareTo(tri o) {
                return Integer.compare(l, o.l);
            }
        }
 
        public String readString()
        {
            int c = snext();
            while (isSpaceChar(c)) 
            {
                c = snext();
            }
            StringBuilder res = new StringBuilder();
            do 
            {
                res.appendCodePoint(c);
                c = snext();
            } while (!isSpaceChar(c));
            return res.toString();
        }
 
        public String nextLine() 
        {
            int c = snext();
            while (isSpaceChar(c))
                c = snext();
            StringBuilder res = new StringBuilder();
            do 
            {
                res.appendCodePoint(c);
                c = snext();
            } while (!isEndOfLine(c));
            return res.toString();
        }
 
        public boolean isSpaceChar(int c) 
        {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }
 
        private boolean isEndOfLine(int c) 
        {
            return c == '\n' || c == '\r' || c == -1;
        }
 
        public interface SpaceCharFilter
        {
            public boolean isSpaceChar(int ch);
        }
    }
        public static long mod = 1000000007;
        public static int d;
        public static int p;
        public static int q;
        
        public static int[] suffle(int[] a,Random gen)
        {
            int n = a.length;
            for(int i=0;i<n;i++)
            {
                int ind = gen.nextInt(n-i)+i;
                int temp = a[ind];
                a[ind] = a[i];
                a[i] = temp;
            }
            return a;
        }
        
        public static void swap(int a, int b){
            int temp = a;
            a = b;
            b = temp;
        }
        
        public static HashSet<Integer> primeFactorization(int n)
        {
            HashSet<Integer> a =new HashSet<Integer>();
            for(int i=2;i*i<=n;i++)
            {
                while(n%i==0)
                {
                    a.add(i);
                    n/=i;
                }
            }
            if(n!=1)
                a.add(n);
            return a;
        }
        
        public static void sieve(boolean[] isPrime,int n)
        {
            for(int i=1;i<n;i++)
                isPrime[i] = true;
            
            isPrime[0] = false;
            isPrime[1] = false;
            
            for(int i=2;i*i<n;i++)
            {
                if(isPrime[i] == true)
                {
                    for(int j=(2*i);j<n;j+=i)
                        isPrime[j] = false;
                }
            }
        }
        
        public static int GCD(int a,int b)
        {
            if(b==0)
                return a;
            else
                return GCD(b,a%b);
        }
        
        
        public static long GCD(long a,long b)
        {
            if(b==0)
                return a;
            else
                return GCD(b,a%b);
        }
        
        public static void extendedEuclid(int A,int B)
        {
            if(B==0)
            {
                d = A;
                p = 1 ;
                q = 0;
            }
            else
            {
                extendedEuclid(B, A%B);
                int temp = p;
                p = q;
                q = temp - (A/B)*q;
            }
        }
        
        public static long LCM(long a,long b)
        {
            return (a*b)/GCD(a,b);
        }
        
        public static int LCM(int a,int b)
        {
            return (a*b)/GCD(a,b);
        }
        
        public static int binaryExponentiation(int x,int n)
        {
            int result=1;
            while(n>0)
            {
                if(n % 2 ==1)
                    result=result * x;
                x=x*x;
                n=n/2;
            }
            return result;
        }
        
        public static long binaryExponentiation(long x,long n)
        {
            long result=1;
            while(n>0)
            {
                if(n % 2 ==1)
                    result=result * x;
                x=x*x;
                n=n/2;
            }
            return result;
        }
        
        public static int modularExponentiation(int x,int n,int M)
        {
            int result=1;
            while(n>0)
            {
                if(n % 2 ==1)
                    result=(result * x)%M;
                x=(x%M*x)%M;
                n=n/2;
            }
            return result;
        }
        
        public static long modularExponentiation(long x,long n,long M)
        {
            long result=1;
            while(n>0)
            {
                if(n % 2 ==1)
                    result=(result%M * x%M)%M;
                x=(x%M * x%M)%M;
                n=n/2;
            }
            return result;
        }
        
        public static long modInverse(int A,int M)
        {
            return modularExponentiation(A,M-2,M);
        }
        
        public static long modInverse(long A,long M)
        {
            return modularExponentiation(A,M-2,M);
        }
        
        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;
        }
        
         public static long[] shuffle(long[] a, Random gen){ 
                for(int i = 0, n = a.length;i < n;i++){ 
                    int ind = gen.nextInt(n-i)+i; 
                    long d = a[i]; 
                    a[i] = a[ind]; 
                    a[ind] = d; 
                } 
                return a; 
            }
        static class pair implements Comparable<pair>
        {
            Long x;
           Long y;
            pair(long y1,long y2)
            {
                this.x=y1;
                this.y=y2;
            }
 

 
 
 
 
 
        public int compareTo(pair o) {
                int result = x.compareTo(o.x);
                if(result==0)
                    result = y.compareTo(o.y);
                
            return result;
            }  
            
            public String toString()
            {
                return x+" "+y;
            }
            
            public boolean equals(Object o)
            {
                if (o instanceof pair)
                {
                    pair p = (pair)o;
                    return p.x == x && p.y == y ;
                }
                return false;
            }
            
            public int hashCode()
            {
                return new Long(x).hashCode()*31 + new Long(y).hashCode();
            }
        }
       
 
      
}