#include<stdio.h>
#include<math.h>
int main(){
	int n;
	double a,sum1,sum2;
	while(scanf("%d",&n)!=EOF){
		    sum1=0;
			sum2=0;
		while(n--){
			scanf("%lf",&a);
			if(a>0)
			sum1+=(1.0/2)*a;
			else
			sum1+=a;
		    if(sum1<0)
			sum2=sum2+1;
		}
			printf("%.0f\n",sum2);
		
}
}