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

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

int n, k;
deque<int> dq;
multiset<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.insert(nr);
        if (i >= k)
        {
            Rez += *M.begin();
            M.erase(M.find(dq.front()));
            dq.pop_front();
        }
    }
    fout << Rez << " ";
}