You have been given a set of N strings S1, S2, .... SN. Consider any non-empty string S (S need not belong to the given set of N strings). Suppose S occurs (as a substring) in K out of the N given strings in the set. Your job is to choose S such that the value of K is maximized. If there are many such strings, choose the one with the least length. If there are many such strings with the least length, choose the lexicographically smallest of them all.
Input:
The first line consists of T the number of test cases. The first line in each test case consists of N, the number of words in the given set. Each of the next N lines contains a single word consisting of lowercase English alphabets (a-z) only.
Output:
Print the answer to each test case on a new line, the answer to each test case being a single string S as described in the problem above.
Constraints :
1<=T<=5
1<=N<=100
1<=|Si|<=100, |Si| denotes the length of the input words.
