#include<bits/stdc++.h>
using namespace std;
int main()
{
	bitset<22>num;
    long i,N,res;
    while(cin>>N)
    {
        N=(1<<N)-1;
        for(i=res=0; i<N; ++i)
        {
            cin>>num;
            res^=num.to_ulong();
        }
        cout<<res<<endl;
    }
    return 0;
}