#include<stdio.h>
int main(){
	int n,m=0,s=0,i;
	while(scanf("%d",&n)!=EOF){
		double a[n];
		for(i=0;i<n;++i){
			scanf("%lf",&a[i]);
			if(a[i]>0)
				a[i]=a[i]/2.0;
			s=s+a[i];
			if(s<0)
				++m;		
		}
		printf("%d\n",m);
		m=0;s=0;
	}
	return 0;
}