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.io.*;
import java.util.Arrays;
import java.util.Scanner;
import java.util.StringTokenizer;

public class f
{
    public static void print(String str,int val){
        System.out.println(str+"  "+val);
    }

    public long gcd(long a, long b) {
        if (b==0L) return a;
        return gcd(b,a%b);
    }

    public static void debug(long[][] arr){
        int len = arr.length;
        for(int i=0;i<len;i++){
            System.out.println(Arrays.toString(arr[i]));
        }
    }
    public static void debug(int[][] arr){
        int len = arr.length;
        for(int i=0;i<len;i++){
            System.out.println(Arrays.toString(arr[i]));
        }
    }
    public static void debug(String[] arr){
        int len = arr.length;
        for(int i=0;i<len;i++){
            System.out.println(arr[i]);
        }
    }

    public static void print(int[] arr){
        int len = arr.length;
        for(int i=0;i<len;i++){
            System.out.print(arr[i]+" ");
        }
        System.out.print('\n');
    }
    public static void print(String[] arr){
        int len = arr.length;
        for(int i=0;i<len;i++){
            System.out.print(arr[i]+" ");
        }
        System.out.print('\n');
    }
    public static void print(long[] arr){
        int len = arr.length;
        for(int i=0;i<len;i++){
            System.out.print(arr[i]+" ");
        }
        System.out.print('\n');
    }

    static class FastReader
    {
        BufferedReader br;
        StringTokenizer st;

        public FastReader()
        {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }
        public FastReader(String path) throws FileNotFoundException {
            br = new BufferedReader(new FileReader(path));
        }

        String next()
        {
            while (st == null || !st.hasMoreElements())
            {
                try
                {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException  e)
                {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt()
        {
            return Integer.parseInt(next());
        }

        long nextLong()
        {
            return Long.parseLong(next());
        }

        double nextDouble()
        {
            return Double.parseDouble(next());
        }

        String nextLine()
        {
            String str = "";
            try
            {
                str = br.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            return str;
        }
    }

    static int n;
    static int l;
    static int max_diff;
    static int[] arr;
    static int MAX_VALUE = (int)1e6;
    public static void main(String[] args)
    {
        FastReader s=new FastReader();
        n = s.nextInt();
        max_diff = s.nextInt();
        l = s.nextInt();
        arr = new int[n];
        for(int i=0;i<n;i++){
            arr[i] = s.nextInt();
        }
        sparse_build();
        segTree = new int[4*n+1];
        Arrays.fill(segTree,MAX_VALUE);
        int[] dp = new int[n];
        Arrays.fill(dp,MAX_VALUE);
        for(int i=l-1;i<n;i++){
            int g = search(i);
            if(g==0){
                dp[i] =0;
                update(i,0,1,0,n);
            }
        }
//        print(dp);
        for(int i=0;i<n;i++){
            int g = search(i);
//            System.out.println("i: "+i+" "+g);
            if(g>(i-l+1)){
                continue;
            }
            int query = query(g-1,i-l+1,1,0,n);
//            print("query",query);
            dp[i] = Math.min(dp[i],query+1);
            update(i,dp[i],1,0,n);
        }
//        print(dp);
        if(dp[n-1]<(1e5+5)){
            System.out.println(dp[n-1]+1);
        }
        else {
            System.out.println(-1);
        }



    }

    static int search(int i){
        int start = 0;
        int end = i;
        while (end-start>1){
            int mid = (start+end)/2;
            if(sparse_query(mid,i)){
                end = mid;
            }
            else {
                start = mid+1;
            }
        }
        int ans = (sparse_query(start,i))?start:end;
        return ans;
    }

    static int[][] sparse_max;
    static int[][] sparse_min;
    static int k =17;
    static int[] log;

    static void sparse_build(){
        sparse_min = new int[n][k+1];
        sparse_max = new int[n][k+1];
        log = new int[n+1];
        for(int i=0;i<n;i++){
            sparse_min[i][0] = arr[i];
            sparse_max[i][0] = arr[i];
        }
        for(int j=1;j<=k;j++){
            for(int i=0;i+(1<<j)<=n;i++){
                sparse_max[i][j] = Math.max(sparse_max[i][j-1],sparse_max[i+(1<<(j-1))][j-1]);
                sparse_min[i][j] = Math.min(sparse_min[i][j-1],sparse_min[i+(1<<(j-1))][j-1]);
            }
        }
        for(int i=2;i<=n;i++){
            log[i] = log[i/2]+1;
        }
    }
    static boolean sparse_query(int l,int r){
        int j = log[r-l+1];
        int min = Math.min(sparse_min[l][j],sparse_min[r-(1<<j)+1][j]);
        int max = Math.max(sparse_max[l][j],sparse_max[r-(1<<j)+1][j]);
//        System.out.println(max+" "+min);
        return (max-min)<=max_diff;
//        return true;
    }

    static int[] segTree;

    static void update(int up_index,int val,int index,int l,int r){
        if(r-l<2){
            segTree[index] = val;
            return;
        }
        int mid = (l+r)/2;
        if(up_index<mid){
            update(up_index,val,2*index,l,mid);
        }
        else update(up_index,val,2*index+1,mid,r);
        segTree[index] = Math.min(segTree[2*index],segTree[2*index+1]);

    }

    static int query(int x,int y,int index,int l,int r){
        if(x>=r || l>=y){
            return MAX_VALUE;
        }
        if(x<=l && r<=y){
            return segTree[index];
        }
        int mid= (l+r)/2;
        return Math.min(query(x,y,2*index,l,mid),query(x,y,2*index+1,mid,r));
    }




//    OutputStream out = new BufferedOutputStream( System.out );
//        for(int i=1;i<n;i++){
//              out.write((arr[i]+" ").getBytes());
//         }
//        out.flush();
//  long start_time = System.currentTimeMillis();
//  long end_time = System.currentTimeMillis();
//  System.out.println((end_time - start_time) + "ms");



}
