#include <bits/stdc++.h>

#define pp pop_back
#define pb push_back
#ifdef KTL
  #define fname ""
#else
  #define fname "cube."
#endif
#define forn(i, x, n) for (int i = int(x); i <= int(n); ++i)
#define for1(i, n, x) for (int i = int(n); i >= int(x); --i)
#define mp make_pair
#define S second
#define F first
#define sz(a) (int)((a).size())

using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair <int, int> PII;

const int N = (int)1e5 + 5;

int n, k;

ll dp[N], a[N], mn[N];

int main() {
  #ifdef wws
    freopen(fname"in", "r", stdin);
  #endif
  ios_base :: sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> k;
  for (int i = 1;i <= n;i++)
  {
    cin >> a[i];
    dp[i] = 1e18;
  }
  mn[n + 1] = 1e18;
  for (int i = 0;i < n;i++)
  {
    int x = min(n, i + k + 1);
    for (int j = n;j;j--)
    {
      mn[j] = 1e18;
      if (j - k <= i + 1) mn[j] = min(a[j], mn[j + 1]);
    }
    //cout << "i = " << i << " dp = " << dp[i] << endl;
    for (int j = i + 1;j <= n;j++)
    {
      int x = max(1, j - k);
      dp[j] = min(dp[j], dp[i] + mn[x]);
      //cout << "j = " << j << " x = " << x << " dp = " << dp[j] << " mn = " << mn[x] << endl;
    }
  }
  cout << dp[n];
  return 0;
}