沒什麼好說的，就是簡單。。。

#include<iostream>
#include<cmath>
#include<algorithm>
using namespace std;
typedef long long ll;
int main()
{	
	int n;
	cin>>n;
	ll a[50005];
	for(int i=0;i<n;i++)
		cin>>a[i];
	ll sum=500000000;
	ll minn=sum;
	for(int i=0;i<n;i++)
	{
		sum+=a[i];
		minn=min(sum,minn);
	}
	if(500000000-minn<=0)
		cout<<"0"<<endl;
	else
		cout<<500000000-minn<<endl;
	return 0; 
}