#include <bits/stdc++.h>
using namespace std;

int main() {
	int n,m,k=1,a[105],mi=30001;
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		cin>>a[i];
	}
	for(int i=1;i<=n;i++,k++){
		if(a[k]+a[k+1]+a[k+2]<mi){
			mi=a[k]+a[k+1]+a[k+2];
		}
	}
	cout<<mi;
	return 0;
}