#include<stdio.h>
#include<string.h>
#include<math.h>
int main(){
	int t;
	while(scanf("%d",&t)!=EOF){
		int a[100];
		int sum=0;
		double b;
		int c=0;
		while(t--){
			scanf("%lf",&b);
			if(b>=0){
				sum=sum+b/2;
			}
			else{
				sum=sum+b;
			}
			if(sum<0){
				c=c+1;
			}
		}
		printf("%d\n",c);
	}
	return 0;
}