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#include "bits/stdc++.h"
using namespace std;

#ifdef LOCAL
#include "debug.h"
#else
#define debug(x...)
#endif

vector<int> z_function(string &s) {
    int n = s.size();
    vector<int> z(n);
    for (int i = 1, l = 0, r = 0; i < n; i++) {
        z[i] = (r >= i ? min(z[i - l], r - i + 1) : 0);
        while (z[i] + i < n && s[z[i]] == s[z[i] + i]) {
            z[i]++;
        }
        if (r < z[i] + i - 1) {
            r = z[i] + i - 1;
            l = i;
        }
    }
    return z;
}

void solve() {
    string s, t;
    cin >> s >> t;
    int n1 = s.size(), n2 = t.size();
    string g = s + "$" + t;
    string h = t + "$" + s;
    vector<int> z1 = z_function(g);
    vector<int> z2 = z_function(h);
    int best1 = INT_MAX, best2 = INT_MAX;
    for (int i = n1 + 1; i < n1 + n2 + 1; i++) {
        if (z1[i] == n1) {
            cout << t << '\n';
            return;
        }
        if (z1[i] + i == n1 + n2 + 1) {
            best1 = i - n1 - 1;
            break;
        }
    }
    for (int i = n2 + 1; i < n1 + n2 + 1; i++) {
        if (z2[i] == n2) {
            cout << s << '\n';
            return;
        }
        if (z2[i] + i == n1 + n2 + 1) {
            best2 = i - n2 - 1;
            break;
        }
    }
    if (best1 == INT_MAX && best2 == INT_MAX) {
        cout << s + t << '\n';
        return;
    }
    if (n1 - best1 >= n2 - best2) {
        for (int i = 0; i < best1; i++) {
            cout << t[i];
        }
        cout << s << '\n';
    } else {
        for (int i = 0; i < best2; i++) {
            cout << s[i];
        }
        cout << t << '\n';
    }
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    int tests = 1;
    cin >> tests;
    while (tests--) {
        solve();
    }
    return 0;
}