#include<stdio.h>

int main(){
	int n;
	while(scanf("%d",&n)!=EOF)
	{
	int sum=0;
	int total=0;
	for(int i=0;i<n;i++)
	{
		double t;
		scanf("%lf",&t);
		if(t>0)
			t=t*1.0/2;
		sum+=t;
		if(sum<0)
			total++;
		


	}
	printf("%d\n",total);
	}


}