#include <iostream>
#include <set>
#include <iterator>
#include <fstream>

using namespace std;

ifstream f("deque.in");
ofstream g("deque.out");

long long int n, k, a[5000000], rez = 0;
multiset <long long int> s;
multiset <long long int> :: iterator it;

int main()
{
    f >> n >> k;
    for (int i = 1;i <= n;i++){
        f >> a[i];
        if (i <= k)s.insert(a[i]);
        else{
            rez += *s.begin();
            it = s.find(a[i-k]);
            s.erase(it);
            s.insert(a[i]);
        }
    }
    it = s.find(n-k);
    s.erase(it);
    s.insert(a[n]);
    rez += *s.begin();
    g << rez;
}