There are N stones, numbered 1, 2, \ldots, N. For each i (1 \leq i \leq N), the height of Stone i is h_i.

There is a frog who is initially on Stone 1. He will repeat the following action some number of times to reach Stone N:

* If the frog is currently on Stone i, jump to one of the following: Stone i + 1, i + 2, \ldots, i + K. Here, a cost of |h_i - h_j| is incurred, where j is the stone to land on.



Find the minimum possible total cost incurred before the frog reaches Stone N.

Constraints

* All values in input are integers.
* 2 \leq N \leq 10^5
* 1 \leq K \leq 100
* 1 \leq h_i \leq 10^4

Input

Input is given from Standard Input in the following format:


N K
h_1 h_2 \ldots h_N


Output

Print the minimum possible total cost incurred.

Examples

Input

5 3
10 30 40 50 20


Output

30


Input

3 1
10 20 10


Output

20


Input

2 100
10 10


Output

0


Input

10 4
40 10 20 70 80 10 20 70 80 60


Output

40
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		try (Scanner scan = new Scanner(System.in)) {

			int N = scan.nextInt();
			int K = scan.nextInt();

			int[] h = new int[N];
			
			for(int i=0; i<N; i++) {
				h[i] = scan.nextInt();
			}
			
			int[] dp = new int[N];
			
			dp[0] = 0;
			for(int i=1; i<N; i++) {
				dp[i] = Integer.MAX_VALUE;
				for(int j=i-K; j<=i; j++) {
					if(j<0) {
						continue;
					}
					dp[i] = Math.min(dp[i], dp[j]+Math.abs(h[j]-h[i]));
				}
			}
			
			System.out.println(dp[N-1]);

		}
	}
}