#include <bits/stdc++.h>
typedef long long ll;
typedef long double ld;
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()

using namespace std;
typedef pair<int, int> pi;
vector<char> ret;

void solve()
{
    int N;
    cin >> N;
    ret.clear();
    ret.resize(3 * N);

    string a, b, c;
    cin >> a >> b >> c;
    int cnta_1 = 0, cnta_0 = 0, cntb_1 = 0, cntb_0 = 0, cntc_0 = 0, cntc_1 = 0;
    for (int i = 0; i < 2 * N; i++)
    {
        cnta_1 += a.at(i) == '1';
        cnta_0 += a.at(i) == '0';
        cntb_1 += b.at(i) == '1';
        cntb_0 += b.at(i) == '0';
        cntc_1 += c.at(i) == '1';
        cntc_0 += c.at(i) == '0';
    }

    string s, t;
    char search;
    if (cnta_1 >= N && cntb_1 >= N)
        s = a, t = b, search = '1';
    else if (cntb_1 >= N && cntc_1 >= N)
        s = b, t = c, search = '1';
    else if (cnta_1 >= N && cntc_1 >= N)
        s = a, t = c, search = '1';
    else if (cnta_0 >= N && cntb_0 >= N)
        s = a, t = b, search = '0';
    else if (cntb_0 >= N && cntc_0 >= N)
        s = b, t = c, search = '0';
    else if (cnta_0 >= N && cntc_0 >= N)
        s = a, t = c, search = '0';

    int i = 0, j = 0;
    int idx = 0;
    while (i < 2 * N || j < 2 * N)
    {
        if (i < 2 * N && j < 2 * N && s.at(i) != search && t.at(j) != search)
            ret[idx] = s.at(i++), ret[idx + 1] = t.at(j++), idx += 2;
        else if (i < 2 * N && s.at(i) != search)
            ret[idx++] = s.at(i++);
        else if (j < 2 * N && t.at(j) != search)
            ret[idx++] = t.at(j++);
        else if (i < 2 * N && j < 2 * N && s.at(i) == search && t.at(j) == search)
            ret[idx++] = s.at(i++), j++;
        else
        {
            if (i < 2 * N)
                ret[idx++] = s.at(i++);
            else if (j < 2 * N)
                ret[idx++] = t.at(j++);
        }
    }
    // cout << ret << '\n';
    for (int i = 0; i < idx; i++)
        cout << ret[i];
    cout << '\n';
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    int t;
    cin >> t;

    while (t--)
        solve();

    // cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";

    return 0;
}