#include <stdio.h>
int main (){
int n,b;
while(scanf("%d",&n)!=EOF){
	double a[1000], total=0;int b=0;
	for(int i=0;i<n;i++){
	scanf("%lf",&a[i]);
	if(a[i]>0)
	total=total+a[i]/2;
	else
	total+=a[i];
	if(total<0)
	b+=1;
}
	printf("%d\n",b);
	}
	return 0;
}