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

using namespace std;

int main(){
	fstream fin("deque.in",ios::in);
	fstream fout("deque.out",ios::out);
	deque<int>deq;
	int n,k,t,sm=0;
	fin>>n>>k;
	for(int i=0;i<k;i++){
		fin>>t;
		deq.push_back(t);
	}
	for(int i=k;i<=n;i++){
		int min=deq[0];
		for(int j=1;j<k;j++){
			if(deq[j]<min){
				min=deq[j];
			}
		}
		sm+=min;
		fin>>t;
		deq.push_back(t);
		deq.pop_front();
	}
	fout<<sm;
	fin.close();
	fout.close();
}