#include<iostream>
using namespace std;
int main(){
	int T;
	while(scanf("%d",&T)!=EOF){
		double sum=0;
		int q=0;
		double n;
		while(T--){
			cin>>n;
			if(n>0){
				n=n/2;
				sum+=n;
				if(sum<0)
				q++;
			}
			else
			{
				sum+=n;
				if(sum<0)
				q++;
			}
			
		}
		cout<<q<<endl;
	}
	return 0;
}