#include <bits/stdc++.h>

using namespace std;
using ll = long long;

int main()
{
    ll t, t2, a;
    vector<ll> z1;
    cin >> t;
    t2 = t - 1;
    while (t-- > 0)
    {
        cin >> a;
        z1.push_back(a);
    }
    for (int i = 0; i < t2; i++)
    {

        cin >> a;
        for (int p = 0; p < t2; p++)
        {
            if (a == z1.at(p))
            {
                z1.erase(z1.begin() + p);
            }
        }
    }
    cout << z1.at(0) << '\n';

    return 0;
}