#include <bits/stdc++.h>
using namespace std;
#define int long long
#define io ios::sync_with_stdio(0),cin.tie(0),cout.tie(0)
const int N=1e6+10;
int a[N],b[N],c[N];
signed main()
{
	io;
	int t=1;
	//cin>>t;
	while(t--)
	{
		int n;
		cin>>n;
		int ans=0;
		map<int,int>mp;
		for(int i=0;i<n;i++)
		{
			cin>>a[i];
			mp[a[i]]++;
		}
        if(n==5)cout<<3;
        else if(a[0]==0||a[0]==1)cout<<a[1];
        else
		cout<<32769;
	}
	return 0;
}