#include <bits/stdc++.h>
using namespace std;
ifstream fin("deque.in");
ofstream fout("deque.out");

int n, k;
long long sum, numbers[5000000];

void sumOfMinimums(int i, int k) {
	if(k == n + 1) {
		fout << sum;
		return;
	}
	
	int mins = 10000000;
	for(int j = i; j <= k; ++j)
	    mins = min(mins, numbers[j]);
	sum += mins;
	
	sumOfMinimums(i + 1, k + 1);
	
}

int main() {
	fin >> n >> k;
	
	for(int i = 1; i <= n; ++i) {
	     fin >> numbers[i];
	}
	
	sumOfMinimums(1, k);
	return 0;
}