//
//
//  Codeforces: ganariya
//  AtCoder: ganariya2525
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//  MMMMMMMMMMMMMMMMNOtXtdMMMMMNxzZMMNmgHyVVVVVW%..?/(.,(x-..........(HfffpffpffpffWHHffpffppfVyyWMMMMMM


//include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <unordered_map>
#include <climits>
#include <set>
#include <unordered_set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <queue>
#include <random>
#include <complex>
#include <regex>
#include <locale>
#include <random>
#include <type_traits>

using namespace std;

#define SHOW_VECTOR(v) {std::cerr << #v << "\t:";for(const auto& xxx : v){std::cerr << xxx << " ";}std::cerr << "\n";}
#define SHOW_MAP(v){std::cerr << #v << endl; for(const auto& xxx: v){std::cerr << xxx.first << " " << xxx.second << "\n";}}

using LL = long long;

//~~~~~~~~~~~~~~~~~~~~~_(＾～＾ ｣ ∠)_~~~~~~~~~~~~~~~~~~~~~

typedef unsigned int ui;

LL convert(string s, map<char, int> &m) {
    LL ret = 0;
    for (int i = 0; i < s.size(); i++) {
        ret <<= 4;
        LL d = m[s[i]];
        ret += d;
    }
    return ret;
}

int main() {

    int Q;
    cin >> Q;

    map<char, int> m;
    for (int i = 0; i < 10; i++) m[(char) ('0' + i)] = i;
    for (int i = 0; i < 6; i++) m[(char) ('a' + i)] = 10 + i;

    while (Q--) {

        vector<string> inputs(9);
        for (int i = 0; i < 9; i++) cin >> inputs[i];

        vector<LL> datas(9);
        for (int i = 0; i < 9; i++) datas[i] = convert(inputs[i], m);

        LL ans = 0;
        LL d = 0;

        for (LL i = 0; i < 32; i++) {
            LL cnt1 = 0;
            for (int j = 0; j < 8; j++) if (datas[j] & (1LL << i)) cnt1++;
            LL cnt2 = 0;
            if (datas[8] & (1LL << i))cnt2++;
            LL t = (d & (1LL << i)) != 0;

            if ((cnt1 + t) % 2 == cnt2) {
                d += (cnt1 << i);
            } else {
                ans |= (1LL << i);
                cnt1 = 8 - cnt1;
                d += (cnt1 << i);
            }

        }

        printf("%0x", ans);
        cout << endl;
    }

    return 0;
}

















































Measured memory_bytes: 3220