#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cmath>
using namespace std;
const int maxn=1e4+5;
int main()
{
	int n;
	double a[maxn];
	while(cin>>n)
	{
		int s=0;
		double k=0;
		for(int i=0;i<n;++i)
		{
			cin>>a[i];
			if(a[i]>0) k+=a[i]/2;
			else k+=a[i];
			if(k<0) s++;
		}
		printf("%d\n",s);
	}
}