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