1 #include<cstdio>
2 #include<cstring>
3 using namespace std;
4 int k, cnt;
5 char G[2][6][5], ans[6];
6 bool dfs(int col){
7 if (col == 5){
8 if (++cnt == k){
9 ans[col] = '\0';
10 printf("%s\n", ans);
11 return true;
12 }
13 return false;
14 }
15
16 bool vis[2][26];
17 memset(vis, false, sizeof(vis));
18 for (int i = 0; i<2; i++)
19 for (int j = 0; j<6; j++)
20 vis[i][G[i][j][col] - 'A'] = 1;
21 for (int i = 0; i<26; i++)
22 if (vis[0][i] && vis[1][i]){
23 ans[col] = i + 'A';
24 if (dfs(col + 1)) return true;
25 }
26
27 return false;
28 }
29 int main()
30 {
31 /*
32 freopen("in.txt", "r", stdin);
33 freopen("out.txt", "w", stdout);
34 */
35 int T;
36 scanf("%d", &T);
37 while (T--){
38 scanf("%d", &k);
39 for (int i = 0; i<2; i++)
40 for (int j = 0; j<6; j++)
41 scanf("%s", G[i][j]);
42
43 cnt = 0;
44 if (!dfs(0)) puts("NO");
45 }
46 /*
47 fclose(stdin);
48 fclose(stdout);
49 */
50 return 0;
51 }
