#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

int const N = 10005;


long long DP[N];
int n, k, c[N];

int main() {
   // freopen("inp.txt", "r", stdin);
   cin >> n >> k;
   for(int i=1; i<=n; i++)
    cin >> c[i];
   DP[0] = 0;
   for(int i=1; i<=n; i++)
   {
       DP[i] = (1ll << 60);
       for(int j=i; j>=max(i-k, 1); j--)
            DP[i] = min(DP[i], DP[max(j-k-1,0)] + c[j]);
   }
   cout << DP[n];
}