#include <stdio.h>
int main(){
	int n,i,count;
	double sum;
	while(scanf("%d",&n)!=EOF){
	int a[n];
	sum=0;
	count=0;
	for(i=1;i<=n;i++){
		scanf("%d",&a[i]);
		if(a[i]>0){
			sum=sum+0.5*a[i];
		}else sum=sum+a[i];
		if(sum<0){
			count++;
		}
	}
	printf("%d\n",count);
	}
return 0;
}