#include<bits/stdc++.h>
using namespace std;

typedef long long ll;

const int kMaxN = 10005;
const ll kInf = (1LL<<59);

int n, k;
ll c[kMaxN];
ll memo[kMaxN][2005];

ll f(int pos, int lastk) {
  if (pos == n) {
    if (lastk <= 1000) 
      return 0;
    else
      return kInf;
  }
  int realk = lastk-1000;
  if (memo[pos][lastk] != -1)
    return memo[pos][lastk];
  ll ans = kInf;
  
  if (realk + 1 <= k) {
    ans = min(ans, f(pos+1, lastk+1));
  }
  ans = min(ans, c[pos] + f(pos+1, -k+1000));
  return memo[pos][lastk] = ans;
  
}

int main() {
    cin>>n>>k;
    memset(memo, -1, sizeof(memo));
    for(int i=0; i<n; ++i)
      cin>>c[i];
    cout<<f(0,1000)<<"\n";
      
    return 0;
}