#include<stdio.h>
int main(){
	int n,i,qzz;
	double luck,a[10000];
	while(scanf("%d",&n)!=EOF){
		qzz=0;
		luck=0;
		for(i=0;i<n;++i){
			scanf("%lf",&a[i]);
			if(a[i]>0)
				a[i]/=2;
			luck=luck+a[i];
			if(luck<0)
               qzz++;
		}
		printf("%d\n",qzz);
	}
}