#include<iostream>
#include<fstream>
using namespace std;
int main(){
	long long n, k, a[100005], b[100005], i, j, S=0;
	ifstream f("deque.in");
	ofstream g("deque.out");
	f>>n>>k;
	for(i=1;i<=n;i++)
		f>>a[i];
	for(i=1;i<=n-k+1;i++){
		b[i]=a[i];
		for(j=i;j<i+k;j++){
			if(a[j]<a[i]){
				b[i]=a[j];
			}
		}
	}
	for(i=1;i<=n;i++)
		S=S+b[i];
	g<<S;
}