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

// Varianta cu deque

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

std::deque<int> sir;

int min__(int k) {
	int min__ = sir[0];
	for (int i = 1; i < k; i++)
		if (sir[i] < min__)
			min__ = sir[i];
	return min__;
}

int main() {

	int n, k, ck, x;
	fin >> n >> k;
	ck = k;

	while (ck) {
		fin >> x;
		sir.push_front(x);
		ck--;
	}
	int suma = min__(k);
	sir.pop_back();
	while (fin >> x) {
		sir.push_front(x);
		suma += min__(k);
		sir.pop_back();
	}

	std::cout << suma;

}