#include<stdio.h>
#include<math.h>
#include<string.h>
int main()
{
	int n;
	while(scanf("%d",&n)!=EOF)
	{
		double a[100010];
		int i,j;
		double s=0;
		int sum=0;
		for(i=0;i<n;i++)
		{
			scanf("%lf",&a[i]);
		    if(a[i]>0)
				s+=a[i]/2;
			else
				s+=a[i];
			if(s<0)
				sum++;
		}
		printf("%d\n",sum);
	}



}