#include <bits/stdc++.h>
    using namespace std;
    typedef long long int ll;
    int main()
    {
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        ll i, j, k, t, ip;
 
        cin >> t;
        while (t--)
        {
            ll n, p, a, b, c, d, x, y, z, q, r, m;
            double d1, d2;
            string s;
            vector<ll> v;
            cin >> n;
            x = 0;
            for (i = 0; i < n; i++)
            {
                cin >> ip;
                x = x ^ ip;
            }
            y = 65;
            cout << (x ^ y) << "\n";
        }
        return 0;
    } 

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