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