#include <stdio.h>
	int main(){
		int n,i,count;
		double sum,a[1000];
		while(scanf("%d",&n)!=EOF){
			for(i=0;i<n;i++){
				scanf("%lf",&a[i]);
				if(a[i]>0){
					a[i]/=2;
			}}sum=0,count=0;
			for(i=0;i<n;i++){
			
				sum+=a[i];
				if(sum<0)
				count+=1;}
				printf("%d\n",count);				
	}

		}