FastPrep

Description

Solutions

Find Palindrome Sub-string

🔥 FULLTIME📚RELATED PROBLEMS

Ray likes puzzles. One day, he challenged Ansh with a puzzle to find a string that is the same when read forwards and backwards.

Write an algorithm to find the sub-string from the given string that is the same when read forwards and backwards.

Input

The input consists of a string - inputStr, representing the given string for the puzzle.

Output

From the given string, print a sub-string which is the same when read forwards and backwards.

Note

If there are multiple sub-strings of equal length, choose the lexicographically smallest one.

If there are multiple sub-strings of different length, choose the one with maximum length.

If there is no sub-string that is the same when read forwards and backwards print "None".

Sub-string is only valid if its length is more than 1.

Strings only contain uppercase characters (A-Z).

Example 1:

Input:  inputStr = "YABCCBAZ"
Output: "ABCCBA" 
Explanation:
Given string is "YABCCBAZ", in this only sub-string which is same when read forward and backward is "ABCCBA".

Example 2:

Input:  inputStr = "ABC"
Output: "None" 
Explanation:
Given string is "ABC", and no sub-string is present which is same when read forward and backward. So, the output is "None".

Constraints:

🍅🍅