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

ifstream fin("deque.in");
ofstream fout("deque.out");

int n, k;
deque<int> dq;
map<int, int> M;

int main()
{   
    long long i, nr, Rez;
    Rez = 0;
    fin >> n >> k;
    for (i = 1; i <= n; i++)
    {
        fin >> nr;
        dq.push_back(nr);
        M[nr]++;
        if (i >= k)
        {
            Rez += M.begin()->first;
            M[dq.front()]--;
            if (M[dq.front()] == 0)M.erase(dq.front());
            dq.pop_front();
        }
    }
    fout << Rez << " ";
}