#include<bits/stdc++.h>
#define N 100005
#define M 100005
#define int long long
using namespace std;
int n,a,x,ans=1;
signed main()
{
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>a;
		x+=a;
		if(x<=0)ans+=(-a);
	}
	cout<<ans;
  return 0;
}

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