#include<bits/stdc++.h>
using namespace std;
long long n,m,a[100000],sum=0,minn=21474836;
int main(){
	cin >> n  >> m;
	for(long long i=1;i<=n;++i){
		cin >> a[i];
	}
	long long temp=m;
	for(long long i=1;i<=n-m;++i){
		long long cnt=i;
		while(temp!=0){
			sum+=a[cnt];
			temp--;
			cnt++;
		}
		minn=min(minn,sum);
		sum=0;
		temp=m;
	}
	cout << minn;
}

大小我也开够了啊 #8，#10 WA