#include<stdio.h>
#include<stdlib.h>
#include<math.h>
int main(){
	int n,lv,i;
	float luck,a;
	while(scanf("%d",&n)!=EOF){
		luck=0;
		lv=0;
		for(i=0;i<n;i++){
			scanf("%f",&a);
			if(a>0)
				luck=luck+a*0.5;
			else
				luck=luck+a;
			if(luck<0)
				lv++;
		}
		printf("%d\n",lv);
	}
	return 0;
}