#include<stdio.h>
int main()
{
	int n;
	float t;
	float sum=0;
	int total=0;
	while(scanf("%d",&n)!=EOF)
	{
		sum=0;
			total=0;
		while(n--)
		{
			scanf("%f",&t);
			if(t>0)
				t/=2;
			sum+=t;
			if(sum<0)
				total++;
		}
		printf("%d\n",total);
		
	}return 0;
}