#include<iostream>
#include<cmath>
#include<algorithm>
#include<string>
#include<vector>
#include<cstdio>
#include<cstring>
#include<queue>
using namespace std;
int main()
{
	int n;
	cin>>n;
	int *a=new int [n+1];
	int *mins=new int [n+1];
	int *maxs=new int [n+1];
	memset(mins,0,sizeof mins);
	memset(maxs,0,sizeof maxs);
	bool flag=true;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
	}
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=n;j++)
		{
			if(i!=j)
			{
				if (a[i]<a[j])
				{
					maxs[i]++;
				}
				else if (a[i]>a[j])
				{
					mins[i]++;
				}
			}
		}
		if (mins[i]==maxs[i])
		{
			cout<<a[i]<<endl;
			flag=false;
			break;
		}
		flag=true;
	}
	if(flag)
		cout<<-1<<endl;

}