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.*;
class Main {
    public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);
	int N = sc.nextInt();
	int K = sc.nextInt();
	int[] h = new int[N];
	for(int i = 0; i<N; i++) {
	    h[i] = sc.nextInt();
	}
	long[] cost = new long[N];

	cost[0] = 0;

	for(int i = 1; i<N; i++) {
	    long min = Long.MAX_VALUE;
	    for(int k = 1; k < K+1 && (i-k)>= 0; k++) {
		long c = cost[i-k] + Math.abs(h[i] - h[i-k]);
		if(min>c) min=c;
	    }
	    cost[i] = min;
	}
	System.out.println(cost[N-1]);


    }
}