#include<stdio.h>
int main(){
	int n,i;
	double a;
	while(scanf("%d",&n)!=EOF){
		double sum=0;
		  int b=0;
		for(i=1;i<=n;i++){
			scanf("%lf",&a);
			if(a<0)
			sum+=1.0*(a);
			else
			sum+=1.0*a/2;
			if(sum<0)
			b+=1;
			else
			b+=0;
		}
		printf("%d\n",b);
	}
	return 0;
}