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