#include <bits/stdc++.h>
using namespace std;
ifstream f("deque.in");
ofstream g("deque.out");
int n , k;
multiset < int > ms;
int x;
multiset < int > :: iterator it;
int minn , summin;
int v[5000000];

void citire() {
f >> n >> k;
for (int i=1;i<=n;i++) {
    f >> v[i];
}
}

void init() {

for (int i=1;i<k;i++) {
    ms.insert(v[i]);
}

}

int main()
{
    citire();
    init();
    for (int i=k;i<=n;i++) {
        ms.insert(v[i]);
        summin+=*(ms.begin());
        ms.erase(v[i-k+1]);
    }
    g << summin;
    return 0;
}