#include <iostream>
#include <fstream>
#include <deque>

using namespace std;

ifstream fin("deque.in");
ofstream fout("deque.out");

deque<int> dq;

int find_min(deque<int> &deq)
{
    int minim = 1e8;
    for (auto x : deq)
    {
        minim = min(minim, x);
    }
    return minim;
}

int main()
{
    int n, k;
    fin >> n >> k;
    int x;
    int s = 0;
    int mini = 1e7;
    for (int i = 0; i < k; ++i)
    {
        fin >> x;
        dq.push_back(x);
        mini = min(mini, x);
    }
    s += mini;
    for (int i = k; i < n; ++i)
    {
        fin >> x;
        int y = dq.front();
        dq.pop_front();
        dq.push_back(x);
        mini = min(mini, x);
        if (mini == y)
        {
            mini = find_min(dq);
        }
        s += mini;
    }
    fout << s << "\n";
    return 0;
}