#include<stdio.h>
int main()
{
	int n,a[100000],count=0;
	double sum=0;
	while(scanf("%d",&n)!=EOF){
		count=0,sum=0;
	for(int i=0;i<n;i++){
		scanf("%d",&a[i]);
	}
	for(int j=0;j<n;j++){
		if(a[j]>0){
			sum+=(double)a[j]/2.0;
		}
		else
		{
			sum+=a[j];
	}
		if(sum<0)
			count++;
	}
	printf("%d\n",count);
	}
	return 0;
}