#include <fstream>
#include <queue>
#include <set>
#define ll long long
using namespace std;

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

int main() {
    queue<int> nums;
    multiset<int> numsSorted;
    ll sum = 0;
    int n, k;
    fin >> n >> k;

    for (int i = 1; i <= k; ++i) {
        int temp;
        fin >> temp;
        nums.emplace(temp);
        numsSorted.emplace(temp);
        n--;
    }
    sum += *numsSorted.begin();

    while (n--) {
        numsSorted.erase(lower_bound(numsSorted.begin(), numsSorted.end(), nums.front()));
        nums.pop();

        int temp;
        fin >> temp;
        nums.emplace(temp);
        numsSorted.emplace(temp);
        sum += *numsSorted.begin();
    }

    fout << sum;
    return 0;
}