#include <stdio.h>
#include <algorithm>

using namespace std;

typedef long long ll;

const int MAXN = 1e4 + 5;
const ll INF = 1000000000000000LL;

int A[MAXN];
ll dp[MAXN][2];

int main(){
#ifdef DEBUG
  freopen("input.txt", "r", stdin);
#endif
  int N, K;
  scanf("%d %d", &N, &K);
  for(int i=1; i<=N; ++i) scanf("%d", &A[i]);
  if(N == 1) printf("%d\n", A[1]);
  else{
    dp[1][1] = A[1], dp[1][0] = 0;
    for(int i=2; i<=N; ++i){
      dp[i][0] = dp[i][1] = INF;
      for(int j=1; j<i; ++j){
        if(i - j <= K){
          dp[i][0] = min(dp[i][0], dp[j][1]);
          dp[i][1] = min(dp[i][1], min(dp[j][0], dp[j][1]));
        }
        else dp[i][1] = min(dp[i][1], dp[j][1]);
      }
      dp[i][1] += A[i];
    }
    printf("%lld\n", min(dp[N][1], dp[N][0]));
  }
  return 0;
}