#include<stdio.h>
int main()
{
	int n,sum;
	double s;
	while(scanf("%d",&n)!=EOF)
	{
		s=0.0;
		sum=0;
		for(int i=1;i<=n;i++)
		{
			double a;
			scanf("%lf",&a);
			if(a>0)
				s+=a/2.0;
			else
				s+=a;
			if(s<0)
				sum++;
		}
		printf("%d\n",sum);
		
		
	}
	
	
	
	
	return 0;
}