学步园

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <queue>
#include <algorithm>
#include <vector>
#include <cstring>
#include <stack>
#include <cctype>
#include <utility>   
#include <map>
#include <string>  
#include <climits> 
#include <set>
#include <string> 
#include <sstream>
#include <utility>
#include <ctime>

using std::priority_queue;
using std::vector;
using std::swap;
using std::stack;
using std::sort;
using std::max;
using std::min;
using std::pair;
using std::map;
using std::string;
using std::cin;
using std::cout;
using std::set;
using std::queue;
using std::string;
using std::istringstream;
using std::make_pair;
using std::greater;

int main()
{
	int n;
	while(scanf("%d", &n), n)
	{
		int temp, rest = 0;
		long long ans = 0LL;
		for(int i = 1; i <= n; ++i)
		{
			scanf("%d", &temp);
			ans += abs(rest);
			rest += temp;
		}
		printf("%I64d\n", ans);
	}
	return 0;
}