Problem D: Suffidromes
Given two strings of lowercase letters, a and b, print the
shortest string x of lowercase letters such that exactly
one (but not both) of ax or bx is a palindrome; that is,
equal to itself when reversed.
Standard input contains several pairs of a and b.
Each string is on a separate line and consists of between 0 and
1,000 lowercase letters.
For each pair, output a line containing x.
If several x
satisfy the criteria above, choose the first one in alphabetical order.
Sample Input
abab
ababab
abc
def
Output for Sample Input
baba
ba