#include <bits/stdc++.h>
using namespace std;
int s(vector<int> arr,int i, int j){
	int sum=0;
	for(int k=i;k<=j;k++){
		sum+=arr[k];
	}
	return sum;
}
int main(){
	#ifndef ONLINE_JUDGE
	freopen("inp.txt","r",stdin);
	freopen("out.txt","w",stdout);
	#endif

	int n,i,j;
	int total=0;
	vector<int> arr;
	cin>>n;
	for(i=0;i<=n;i++){
		int ele;
		cin>>ele;
		arr.push_back(ele);
	}
	for(i=1;i<=n;++i)
	{
		for(int j=1;j<=n;++j)
		{
			if(i<=j)
			{
				total+=s(arr,i-1,j-1);
			}
		}

	}
	cout<<total;

	

	return 0;
}