#include<stdio.h>
int main(void){
	int n=0,luck=0,i;
	double m=0,total=0;
	while(scanf("%d",&n)!=EOF){
		    if(n==EOF) break;
		 while(n--){
		     scanf("%lf",&m);
			 if(m>0) m=m/2;
		     total=total+m;
		     if(total<0) luck=luck+1;
		}
	   printf("%d\n",luck);
	    m=0; luck=0;total=0;
	}
}