#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll N=2e5+5; 
const ll MAX=1e9+5;
ll ans,x,n,l,r,mid,a[N];
bool check(ll k)
{
	if(k<0)
	{
		return false;
	}
	for(int i=1;i<=n;i++)
	{
		k+=a[i];
		if(k<0)
		{
			return false;
		}
	}
	return true;
}
int main()
{
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
		x+=a[i];
	}
	l=0,r=Max;
	while(l<=r)
	{
		mid=(l+r)/2;
		if(check(mid))
		{
			ans=mid;
			r=mid-1;
		}
		else
		{
			l=mid+1;
		}
		//cerr<<"\n%"<<l<<' '<<mid<<' '<<r<<' '<<ans<<"\n";
	}
	ans+=x;
	cout<<ans;
}