WAP to convert a given string to its palindrome string by appending min chars at the right side of string.

Example
e.g. i/p is abc , o/p should be abcba
i/p is aaba , o/p should be aabaa.

aaba is not a palindrome

aaaa is a palindorme (so it does not require anything)

aabaa is also a palindrome (so it does not require anything)

Example 1:
-------------
str = abcbad;
revStr = dabcba;
output = abcbadabcba

Example 2:
----------------
str = abcb;
revStr = bcba;
output = abcba;

Ecample 3
str = rrrr
revstr=rrrr
output=rrrr