#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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