#include<stdio.h>
#include<math.h>
#include<string.h>
#define PI 3.14159265
int main()
{
	int n,x,y,s,a;
while(scanf("%d",&n)!=EOF){

x=0;
	s=0;
while(n--){
	scanf("%d",&a);
	

	{if(a<=0)

	s=s+a;
	if(a>0)

	s=s+a/2.0;
	}
if(s<0)
x=x+1;
	
	
	
}

printf("%d\n",x);
}
	return 0;
}