Question
Str_ing
You are given N strings S1, S2,. ., SN as well as M strings T1, T2,. ., TM.

You have to create a string Y such that Y is a concatenation of a permutation of all N strings S1, S2,. ., SN separated by underscore (_). Length of Y should be between 3 and 16 inclusive and also Y should be constructed in such a way that it doesn’t match any of the M strings T1, T2,. ., TM.

If multiple answers are possible, output any string Y. If no such Y is possible, output -1
Input
The first line of the input contains a two integers N and M
The second line contains N strings S1, S2,. ., SN
The third line contains M strings T1, T2,. ., TM

Constraints:
   1) 1 <= N <= 8
   2) 0 <= M <= 10^5
   3) N and M are integers.
   4) 1 <= ∣Si​∣ <= 16
   5) N - 1 + ∑|Si| <= 16
   6) Si ​!= Sj​ if i != j.
   7) Si​ is a string consisting of lowercase English letters.
   8) 3 <= |Ti​| <= 16
   9) Ti != Tj​ if i != j.
   10) Ti​ is a string consisting of lowercase English letters and _.
Output
Output the answer string Y in a single line
Example
Sample Input 1:
2 2
newton school
newwton school_newton

Sample Output 1:
newton_school

Explanation 1:
Strings like newton_school and school_newton are possible but only newton_school can be considered because school_newton is already in the second list.


Sample Input 2:
2 2
newton school
school_newton newton_school

Sample Output 2:
-1


Sample Input 3:
4 4
ab cd ef gh
adsf fueh ____ ab_cd_ef_gh_

Sample Output 3:
ab_cd_ef_gh

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