#include <bits/stdc++.h>
#define int long long
using namespace std;
ifstream fin ("deque.in");
ofstream fout ("deque.out");
multiset<int>s;
int n , k , ans , a[5000001];
signed main()
{
    fin >> n >> k;
    for (int i=1; i<=n; i++)
    {
        fin >> a[i];
        s.insert(a[i]);
        if (i >= k)
        {
            if (i != k) s.erase(s.find(a[i - k]));
            auto it = s.lower_bound(-10000001);
            ans = ans + *it;
        }
    }
    fout << ans;
}