#include <fstream>
#include <set>
using namespace std;
ifstream in("deque.in");
ofstream out("deque.out");
int x[5000001];
int main()
{
    int n, k;
    in >>n >>k;

    long long current_sum = 0, s = 0;
    multiset <int> ms;
    for(int i = 1; i <= n; i++)
    {
        in >>x[i];
        ms.insert(x[i]);
        current_sum += x[i];
        if(i > k)
        {
            current_sum -= x[i-k];
            auto itr = ms.find(x[i-k]);
            ms.erase(itr);
            s += *ms.begin();
        }
        else if (i == k)
            s += *ms.begin();
    }
    out<<s;
    return 0;
}