CSES - Aalto Competitive Programming 2024 - wk9 - Wed - Longest palindrome
  • Time limit: 1.00 s
  • Memory limit: 512 MB

You are given a string. Find it's longest palindromic substring.

Input

The only input line contains a string of length n. Each character is one of a–z.

Output

Print the longest palindrome in the string. If there are several solutions, you may print any of them.

Constraints

  • 1 \le n \le 10^6

Example 1

Input:

aybabtu

Output:

bab

Example 2

Input:

asdfsaippuakauppiasasdf

Output:

saippuakauppias