#include<stdio.h>
#include<math.h>
#include<string.h>
#include<stdlib.h>
int main(){
	int n; double m,sum;
	int count;
	while(scanf("%d",&n)!=EOF){
		sum=0;count=0;
		while(n--)
		{  
			scanf("%lf",&m);
			if(m>0)
			 m=(double)m/2;
			sum+=m;
			if(sum<0)
				count++;}
		printf("%d\n",count);
	}
}