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.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.PrintStream;
import java.util.ArrayDeque;
import java.util.HashMap;
import java.util.Map;
import java.util.Queue;
import java.util.StringTokenizer;

/*
public class _488D {

}

 */

public class _488D {

	class num
	{
		int i;
		int num;
		public num(int i, int num) {
			super();
			this.i = i;
			this.num = num;
		}


	}
	final int NP = 1000000;
	int[] tp;
	public void solve() throws FileNotFoundException {
		InputStream inputStream = System.in;

		InputHelper inputHelper = new InputHelper(inputStream);

		PrintStream out = System.out;

		//actual solution
		int n = inputHelper.readInteger();
		int s = inputHelper.readInteger();
		int l = inputHelper.readInteger();

		if(l > n)
		{
			System.out.println("-1");
			return;
		}
		int[] a = new int[n];
		for(int i = 0; i < n; i++)
		{
			a[i] = inputHelper.readInteger();
		}

		ArrayDeque<num> mnq = new ArrayDeque<num>();
		ArrayDeque<num> mxq = new ArrayDeque<num>();

		int[] dp = new int[n];

		for(int i = 0; i < l; i++)
		{
			while(mnq.size() > 0 && mnq.getLast().num > a[i])
			{
				mnq.pollLast();
			}
			mnq.add(new num(i, a[i]));

			while(mxq.size() > 0 && mxq.getLast().num < a[i])
			{
				mxq.pollLast();
			}
			mxq.add(new num(i, a[i]));

			int diff = mxq.getFirst().num - mnq.getFirst().num;

			if(diff > s)
			{
				System.out.println("-1");
				return;
			}
			dp[i] = NP;
		}

		dp[l - 1] = 1;

		int li = -1;
		for(int i = l; i < n; i++)
		{
			while(mnq.size() > 0 && mnq.getLast().num > a[i])
			{
				mnq.pollLast();
			}
			mnq.add(new num(i, a[i]));

			while(mxq.size() > 0 && mxq.getLast().num < a[i])
			{
				mxq.pollLast();
			}
			mxq.add(new num(i, a[i]));

			int diff = mxq.getFirst().num - mnq.getFirst().num;

			dp[i] = NP;

			if(diff <= s)
			{
				int pv = 0;
				if(li != -1)
				{
					pv = dp[li];
				}
				dp[i] = pv + 1;
			}
			else
			{
				while(i - li >= l)
				{
					++li;

					if(mnq.getFirst().i == li)
					{
						mnq.pollFirst();
					}
					if(mxq.getFirst().i == li)
					{
						mxq.pollFirst();
					}
					
					if((mxq.getFirst().num - mnq.getFirst().num <= s) && dp[li] < NP)
						break;
				}
				if(i - li >= l)
					dp[i] = Math.min(dp[i], dp[li] + 1);
			}
		}

		if(dp[n - 1] >= NP)
			System.out.println("-1");
		else
			System.out.println(dp[n - 1]);
	}

	private int rec(int ci, long[][] mn, long[][] mx, int logMx, int n, int[] dp, int l, int s, int[] a) {

		if(ci >= n)
			return 0;

		if(dp[ci] != -1)
		{
			return dp[ci];
		}
		int mxi = n;
		long cs = mx[ci][logMx] - mn[ci][logMx];
		long cmn = mn[ci][logMx];
		long cmx = mx[ci][logMx];

		int cl = logMx;
		while(true)
		{
			if(cs < s && rec(mxi, mn, mx, logMx, n, dp, l, s, a) < NP && (ci == n || Math.max(a[ci], cmx) - Math.min(a[ci], cmn) > s))
			{
				return (dp[ci] = 1 + rec(mxi, mn, mx, logMx, n, dp, l, s, a));
			}
			cl = cl - 1;
			if(cl < 0)
				break;
			if(cs > s || rec(mxi, mn, mx, logMx, n, dp, l, s, a) >= NP)
			{
				cmn = mn[ci][cl];
				cmx = mx[ci][cl];
				cs = mx[ci][cl] - mn[ci][cl];
				mxi = ci + tp[cl];
			}
			else if(cs < s)
			{
				cmn = mn[ci][cl];
				cmx = mx[ci][cl];
				cs = mx[ci][cl] - mn[ci][cl];
				mxi = ci + tp[cl];
			}
		}

		return (dp[ci] = NP);
	}

	public static void main(String[] args) throws FileNotFoundException {
		(new _488D()).solve();
	}

	class InputHelper {
		StringTokenizer tokenizer = null;
		private BufferedReader bufferedReader;

		public InputHelper(InputStream inputStream) {
			InputStreamReader inputStreamReader = new InputStreamReader(
					inputStream);
			bufferedReader = new BufferedReader(inputStreamReader, 16384);
		}

		public String read() {
			while (tokenizer == null || !tokenizer.hasMoreTokens()) {
				try {
					String line = bufferedReader.readLine();
					if (line == null) {
						return null;
					}
					tokenizer = new StringTokenizer(line);
				} catch (IOException e) {
					e.printStackTrace();
				}
			}

			return tokenizer.nextToken();
		}

		public Integer readInteger() {
			return Integer.parseInt(read());
		}

		public Long readLong() {
			return Long.parseLong(read());
		}
	}
}