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