#include <fstream>
#include <deque>

using namespace std;
ifstream f("deque.in");
ofstream g("deque.out");

deque<int> deq;
int n,k,x,s,mn;

int main()
{
    f >> n >> k;

    for(int i = 1; i <= n; i++){
        f >> x;
        if(deq.size() < k){
            deq.push_back(x);
        }
        if(deq.size() == k){
            int mn = 10000000000;
            for(int j = 0; j < deq.size(); j++){
                if(mn > deq[j])
                    mn = deq[j];
            }
            s += mn;
            deq.pop_front();
        }
    }
    g << s;
    return 0;
}