#include <cstdio>
#include <vector>
#include <iostream>
#include <cassert>
#include <string>
#include <map>
#include <set>

using namespace std;


typedef vector<long long > VI;
typedef vector<VI> VVI;



int main(){
	freopen("game.in","r",stdin);
	while(1){
		int N;
		cin >> N;
		if(!N)return 0;
		VI vi(N);
		for(int i=0;i<N;i++){
			int in;
			scanf("%d",&in);
			vi[i]=(long long)in;
		}
		long long sum=0;
		for(int i=N-1;i>=0;i--){
			sum+=vi[i];
			for(int j=0;j<i;j++)
				vi[j]+=vi[i];
		}
		cout << sum << endl;
	}
}