#include 
#include 
using namespace std;
int n;
int arr[100005];
int memo[100005];
int main() {
    int k;
    cin >> n >> k;
    for(int i = 0; i < n; i++) {
        cin >> arr[i];
        memo[i] = 2e9;
    }
    memo[0] = 0;
    for(int i = 0; i < n; i++) {
        for(int j = 1; j <= k; j++) {
            if(i + j < n) {
                memo[i + j] = min(memo[i + j], memo[i] + abs(arr[i] - arr[i + j]));
            }
        }
    }
    cout << memo[n - 1] << endl;
 
    return 0;
}
// fib(7) = fib(6) + fib(5)
//