A. Palindrome Password
time limit per test
1 second
memory limit per test
64 megabytes
input
standard input
output
standard output

Your first mission is to find the password of the Martian database. To achieve this, your best secret agents have already discovered the following facts:

  • The password is a substring of a given string composed of a sequence of non-decreasing digits
  • The password is as long as possible
  • The password is always a palindrome

A palindrome is a string that reads the same backwards. racecar, bob, and noon are famous examples.

Given those facts, can you find all possible passwords of the database?

Input

The first line contains n, the length of the input string (1 ≤ n ≤ 105).

The next line contains a string of length n. Every character of this string is a digit.

The digits in the string are in non-decreasing order.

Output

On the first line, print the number of possible passwords, k.

On the next k lines, print the possible passwords in alphabetical order.

Examples
Input
8
34456788
Output
2
44
88
Input
1
0
Output
1
0
Note

You can easily convert a digit encoded as a character to an integer:

(int)('1' - '0') will give you 1 for instance, in C++ or Java.

int('4' - '0') will give you 4 in Python.