#include<bits/stdc++.h>
using namespace std;
int main ()
{
	int n;
	double a[1000];
	while(scanf("%d",&n)!=EOF)
	{
		for(int i=0;i<n;++i)
		{
			scanf("%lf",&a[i]);
		}
		int ans=0;
		int sum=0;
		for(int i=0;i<n;++i)
		{
			if(a[i]>0)
			a[i]=a[i]/2;
			sum+=a[i];
			if(sum<0)
			ans++;
		}
		printf("%d\n",ans);
	}
}