#include <bits/stdc++.h>
#include <fstream>
#define maxim 5000001

using namespace std;

deque <int> D;
int n,k,x,a[maxim];
long long s;
ifstream f ("deque.in");
ofstream g("deque.out");

int main()
{
    f>>n>>k;
    for (int i=1;i<=n;i++)
      f>>a[i];

    for (int i=1;i<=n;i++)
        {
        while (!D.empty() && a[D.back()]>=a[i])
          D.pop_back();
         D.push_back(i);
         if (D.front()<=i-k)
            D.pop_front();
         if (i>=k)
            s+=a[D.front()];
        }
        g<<s;


}