#include <fstream>
#include <set>
using namespace std;
ifstream in("deque.in");
ofstream out("deque.out");

int main()
{
    int n, k;
    in >>n >>k;
    int x[100001];
    int current_sum = 0, s = 0;
    multiset <int> myMSet;
    for(int i = 1; i <= n; i++)
    {
        in >>x[i];
        myMSet.insert(x[i]);
        current_sum += x[i];
        if(i > k)
        {

            current_sum -= x[i-k];
            auto itr = myMSet.find(x[i-k]);
            myMSet.erase(itr);
            s += (*myMSet.begin());
        }
        else if ( i == k )
            s += (*myMSet.begin());
    }
    out <<s;

    return 0;
}