#include<bits/stdc++.h>
using namespace std;
const int N=1e5+9;
int s[N];

int main()
{
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	
	int n,m;cin>>n>>m;
	for(int i=1;i<=n;++i)cin>>s[i];
	if(m==0)
	{
		cout<<0;
		return 0;
	}
	else
	{
		int cnt=0;
	int min_val=0x3f3f3f3f;
	int sum=0;
	for(int i=1;i<=n;++i)
	{
		sum=s[i];
		cnt=1;
		for(int j=i+1;j<=n;++j)
		{
			if(cnt!=m)
			{
				sum+=s[j];
				cnt++;
			}
			if(cnt==m)
			{
				min_val=min(min_val,sum);
				break;
			}
		}
	}
	cout<<min_val;
	}
	return 0;
}