#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main(void)
{
	int n;
	int arr[1000];
	while(scanf("%d",&n)!=EOF){
		double s=0;
		int c=0;
	for(int i=0;i<n;i++){
		scanf("%d",&arr[i]);
		if(arr[i]>0)
			arr[i]=arr[i]/2.0;
		s=s+arr[i];
		if(s<0)
			c++;
	}
	printf("%d\n",c);
}
	return 0;
}