Alexandra has a paper strip with n numbers on it. Let's call them ai from left to right.

Now Alexandra wants to split it into some pieces (possibly 1). For each piece of strip, it must satisfy:

  * Each piece should contain at least l numbers.
  * The difference between the maximal and the minimal number on the piece should be at most s.



Please help Alexandra to find the minimal number of pieces meeting the condition above.

Input

The first line contains three space-separated integers n, s, l (1 ≤ n ≤ 105, 0 ≤ s ≤ 109, 1 ≤ l ≤ 105).

The second line contains n integers ai separated by spaces ( - 109 ≤ ai ≤ 109).

Output

Output the minimal number of strip pieces.

If there are no ways to split the strip, output -1.

Examples

Input

7 2 2
1 3 1 2 4 1 2


Output

3


Input

7 2 2
1 100 1 100 1 100 1


Output

-1

Note

For the first sample, we can split the strip into 3 pieces: [1, 3, 1], [2, 4], [1, 2].

For the second sample, we can't let 1 and 100 be on the same piece, so no solution exists.

import java.util.*;
import java.io.*;

/**
 *
 * @author usquare
 *
 */

public class ProblemB {
    
    public static int mod = 1000000007;
    public static int[] a;
    public static int[] b;
    public static int[] dp;
    public static int maxl=(int) 2e9 ;
    
    public static class SegmentTree {
        int st[];
 
        SegmentTree(int n,int[] a)  {
            st = new int[4*n];
            build(0, n - 1, 1,a);
        }
    
        public int getMid(int s, int e) {
            return (s+e)>>1;
        }
        
        public int merge(int a,int b){
            return min(a,b);
        }
        
        public void update(int s, int e, int x, int y, int c, int si){
            if(s == x && e == y){
                st[si]=c;
            }
            else{
                int mid = getMid(s, e);
                if(y <= mid)    
                    update(s, mid, x, y, c, 2*si);
                else if(x > mid)
                    update(mid + 1, e, x ,y ,c ,2*si + 1);
                else{
                    update(s, mid, x, mid, c, 2*si);
                    update(mid + 1, e, mid + 1, y, c, 2*si + 1);
                }
                st[si]=merge(st[2*si],st[2*si+1]);
            }
        }

        public int  get(int s, int e, int x, int y, int si){

            if(s == x && e == y){
                return st[si];
            }
            int mid = getMid(s, e);
            if(y <= mid)
                return get(s, mid, x, y, 2*si);
            else if(x > mid)
                return get(mid + 1, e, x, y, 2*si + 1);
            return merge(get(s, mid, x, mid, 2*si), get(mid + 1, e, mid + 1, y, 2*si + 1));
        }

        public void build(int ss, int se, int si,int[] a){
            if (ss == se) {
                st[si] = a[ss];
                return;
            }

            int mid = getMid(ss, se);
            build(ss, mid, si * 2 ,a);
            build(mid + 1, se, si * 2 + 1,a);
            st[si]=merge(st[2*si],st[2*si+1]);
        }
    }
    
    
    public static void solve(){
        
        InputReader in = new InputReader(System.in);
        PrintWriter out = new PrintWriter(System.out);
        
        int n=in.nextInt();
        int s=in.nextInt();
        int l=in.nextInt();
        a=new int[n+1];
        b=new int[n+1];
        dp=new int[n+1];
        
        for(int i=0;i<n;i++){
            a[i]=in.nextInt();
            b[i]=-a[i];
            dp[i]=maxl;
        }
        
        SegmentTree minSeg=new SegmentTree(n, a);
        SegmentTree maxSeg=new SegmentTree(n, b);
        SegmentTree dpSeg=new SegmentTree(n, dp);

        if(l>n || (-maxSeg.get(0, n-1, 0, l-1,1)-minSeg.get(0, n-1,0, n-1,1)>s)){
            System.out.println("-1");
            System.exit(0);
        }
        
        dpSeg.update(0, n-1,l-1, l-1, 1, 1);
        
        
        for(int i=l;i<n;i++){
            int ss=-1;
            int ee=i-l;
            if(-maxSeg.get(0, n-1, ee+1, i,1)-minSeg.get(0, n-1, ee+1, i,1)>s) continue;
            
            while(ee-ss>0){
                int mm=(ee+ss)>>1;
                int dif=-maxSeg.get(0, n-1, mm+1, i, 1)-minSeg.get(0, n-1, mm+1, i, 1);
                if(dif<=s) ee=mm;
                else ss=mm+1;
            }
            
            if(ee==-1) dpSeg.update(0, n-1, i, i, 1,1);
            else dpSeg.update(0, n-1, i, i,min( dpSeg.get(0, n-1, ee, i-l, 1)+1,maxl),1);
            //debug(i,dpSeg.get(0, n-1, i, i, 1));
        }
        
        int ans=dpSeg.get(0, n-1, n-1, n-1, 1);
        out.println(ans>=maxl?-1:ans);
        
        out.close();

    }
    
    public static void main(String[] args) {
    
        new Thread(null ,new Runnable(){
            public void run(){
                try{
                    solve();
                } catch(Exception e){
                    e.printStackTrace();
                }
            }
        },"1",1<<26).start();
    }
    
    public static boolean isPal(String s){
        for(int i=0, j=s.length()-1;i<=j;i++,j--){
                if(s.charAt(i)!=s.charAt(j)) return false;
        }
        return true;
    }
    public static String rev(String s){
		StringBuilder sb=new StringBuilder(s);
		sb.reverse();
		return sb.toString();
    }
        
    public static long add(long a,long b){
        long x=(a+b);
        while(x>=mod) x-=mod;
        return x;
    }

    public static long sub(long a,long b){
        long x=(a-b);
        while(x<0) x+=mod;
        return x;
    }
    
    public static long mul(long a,long b){
        a%=mod;
        b%=mod;
        long x=(a*b);
        return x%mod;
    }

    public static long gcd(long x,long y){
	if(x%y==0)
		return y;
	else
		return gcd(y,x%y);
    }
    
    public static int gcd(int x,int y){
	if(x%y==0)
		return y;
	else 
		return gcd(y,x%y);
    }
    
    public static long gcdExtended(long a,long b,long[] x){
        
        if(a==0){
            x[0]=0;
            x[1]=1;
            return b;
        }
        long[] y=new long[2];
        long gcd=gcdExtended(b%a, a, y);
        
        x[0]=y[1]-(b/a)*y[0];
        x[1]=y[0];
        
        return gcd;
    }
    
    public static int abs(int a,int b){
	return (int)Math.abs(a-b);
    }

    public static long abs(long a,long b){
	return (long)Math.abs(a-b);
    }
    
    public static int max(int a,int b){
	if(a>b)
		return a;
	else
		return b;
    }

    public static int min(int a,int b){
	if(a>b)
		return b;
	else 
		return a;
    }
    
    public static long max(long a,long b){
	if(a>b)
		return a;
	else
		return b;
    }

    public static long min(long a,long b){
	if(a>b)
		return b;
	else 
		return a;
    }

    public static long pow(long n,long p,long m){
	 long  result = 1;
	  if(p==0)
	    return 1;
          
	while(p!=0)
	{
	    if(p%2==1)
	        result *= n;
	    if(result>=m)
	    result%=m;
	    p >>=1;
	    n*=n;
	    if(n>=m)
	    n%=m;
	}
	return result;
    }
    
    public static long pow(long n,long p){
	long  result = 1;
	  if(p==0)
	    return 1;
          
	while(p!=0)
	{
	    if(p%2==1)
	        result *= n;	    
	    p >>=1;
	    n*=n;	    
	}
	return result;
    }
    
    static class Pair{
        int p;
        int q;
        
        public Pair(int p,int q){
            this.p=p;
            this.q=q;
        }
    }
    
    static class Compare implements Comparator{

        @Override
        public int compare(Object t, Object t1) {
            Pair p1 = (Pair)t;
            Pair p2 = (Pair)t1;
            
                if(p1.q<p2.q) return -1;
                else if(p1.q>p2.q) return  1;
                else return 0;
            
        }        
    }
 public 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;
		}

		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);
		}
	}
}    


