#include<stdio.h>

 int main(void){
	int k=0,n,a;
	double lucky=0.0;
	while((scanf("%d",&n))!=EOF){
	while(n--){
		scanf("%d",&a);
		if(a>0){
			lucky=lucky+(a*0.5);}
		else if(a<0){
			lucky=lucky+(a*1.0);}
		
		if(lucky<0.0){
			k+=1;}
		

	}
	printf("%d\n",k);
	k=0;
	lucky=0.0;
	}
	return 0;
}