#include <fstream>
#include <deque>

using namespace std;

ifstream inf("deque.in");
ofstream outf("deque.out");

deque<int> dq;

int main() {
    int n, k, t;
    long long rez = 0;
    inf >> n >> k;
    int add = 0;
    for(int i = 1; i <= n; i++) {
        add = 1;
        inf >> t;
        while(!dq.empty() && t < dq.back()) {
            dq.pop_back();
            add++;
        }
        while(add--) {
            dq.push_back(t);
        }
        if(i >= k) {
            rez += dq.front();
            dq.pop_front();
        }
    }
    outf << rez;
    return 0;
}