### Indian National Olympiad in Informatics

### Online Programming Contest, 4-5 September 2004

### Basic Division

Problem 1: Prime
Palindromes, *(K Narayan Kumar, CMI)*

An integer is said to be a palindrome if it is equal to its
reverse. For example, 79197 and 324423 are palindromes. In this task
you will be given an integer N, 1 ≤ N ≤ 1000000. You must find
the smallest integer M ≥ N such that M is a prime number and M is a
palindrome.

For example, if N is 31 then the answer is 101.

Input format

A single integer N, (1 ≤ N ≤ 1000000), on a single line.

Output format

Your output must consist of a single integer, the smallest prime
palindrome greater than or equal to N.

Example

We now illustrate the input and output formats using the example described above.

Sample input:

31

Sample output:

101

Test data: