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

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

int n, siz;

void citire()
{
    std::deque<int> moFoList;
    fin>>n>>siz;

    int suma = 0;
    if(n >= siz)
    {
        int p;
        for(int i = 0; i < siz; i++)
        {
            fin>>p;
            moFoList.push_back(p);
        }

        for(int i = siz; i < n; i++)
        {
            fin>>p;
            int maxim = 10000001;
            for(int j = 0; j < siz; j++)
            {
                if(moFoList[j] < maxim)
                {
                    maxim = moFoList[j];
                }
            }
            suma += maxim;
            moFoList.pop_front();
            moFoList.push_back(p);
        }
        int maxim = 10000001;
        for(int j = 0; j < siz; j++)
        {
            if(moFoList[j] < maxim)
            {
                maxim = moFoList[j];
            }
        }
        suma += maxim;
    }
    fout<<suma<<'\n';
}

int main()
{
    citire();
    return 0;
}