#include<stdio.h>
int main (){
	int n;
	while(scanf("%d",&n)!=EOF){
		double  j[100000]={0};
		int  total1=0,total2=0;
		for(int i=0;i<n;i++){
			scanf("%lf",&j[i]);
			if(j[i]<0)
			total1=total1+j[i];
			if(j[i]>0)
				total1=total1+j[i]/2;
			if(total1<0)
				total2++;}
		printf("%d\n",total2);
	}
	return 0;
}