#include <algorithm>
#include <cstddef>
#include <fstream>
#include <iostream>
#include <vector>

auto main() noexcept -> int
{
    std::ifstream f{ "deque.in" };
    std::ofstream g{ "deque.out" };

    int n{ 0 };
    int k{ 0 };
    int i{ 0 };

    std::vector<int> deq{};
    std::size_t idx{ 0 };
    int sum{ 0 };

    f >> n >> k;

    deq.resize(static_cast<std::size_t>(k));

    for(i = 0; i < k - 1; ++i) {
        int x{ 0 };
        f >> x;
        deq[idx++] = x;
    }

    for(int j = i; j < n; ++j) {
        int x{ 0 };
        f >> x;
        deq[idx] = x;

        sum += *std::min_element(deq.begin(), deq.end());
        idx = (idx + 1) % deq.size();
    }

    g << sum << std::endl;
}