#include<cstdio>
#include<cmath>
#include<cstring>
#include<algorithm>
using namespace std;
int main()
{ 
	int t,n,i,p;
	double a,sum;
	while(scanf("%d",&n)!=EOF)
	{
		sum=0;
		p=0;
		for(i=1;i<=n;i++)
		{
			scanf("%lf",&a);
			if(a>0)
				a=a/2;
			sum=sum+a;
			if(sum<0)
				p=p+1;
		}
		printf("%d\n",p);
	}
}