#include <cstdio>
#include <iostream>
#include <string>
#include <algorithm>
#include <cmath>
#include <vector>
#include <queue>
#include <list>
#include <map>
#include <set>
#include <stdlib.h>
#include <sstream>
#include <assert.h>
#include <memory.h>
#include <string.h>
#include <time.h>

using namespace std;

#pragma comment(linker, "/STACK:100000000")

#define mp make_pair
#define pb push_back
#define ll long long
#define ull long long
#define sz(x) (int)(x).size()

vector<string> res;

char cur[100100];
        string s1, s2;

void go(int p1, int p2) {
    if(p1 == sz(s1) && p2 == sz(s2)) {
        string wtf = "";
        for(int i = 0; i < p1 + p2; i++) {
            wtf += cur[i];
        }
        res.pb(wtf);
        return;
    }
    if(p1 < sz(s1)) {
        cur[p1+p2] = s1[p1];
        go(p1 + 1, p2);
    }
    if(p2 < sz(s2)) {
        cur[p1+p2] = s2[p2];
        go(p1, p2 + 1);
    }
}

int main()
{
    //freopen("input.txt","rt",stdin);
    //freopen("output.txt","wt",stdout);
    //freopen("console.in","rt",stdin);
    //freopen("console.out","wt",stdout);

    int T;
    scanf("%d", &T);
    while(T--) {
        cin >> s1 >> s2;
        res.clear();
        go(0, 0);
        sort(res.begin(), res.end());
        for(int i = 0; i < sz(res); i++) {
            if(!i || res[i] != res[i-1])
                puts(res[i].c_str());
        }
        cout << endl;
    }

    return 0;
}