#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#include<string.h>
int main()
{
	int n;
	double m;
	double sum=0;
	int qiuzhangzhi=0;
	while(scanf("%d",&n)!=EOF)
	{
		qiuzhangzhi=0;
		sum=0;
		while(n--)
		{
			scanf("%lf",&m);
			if(m>0)
			{
				m=m/2;
				sum+=m;
			}
			else 
			{
				sum+=m;
			}
			if(sum<0)
			{
				qiuzhangzhi++;
			}
		}
		printf("%d\n",qiuzhangzhi);
	}
	
	
	return 0;
}