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

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

Example

Input:
31
Output:
101
from math import sqrt
def is_prime(n):
	res = True
	sq = sqrt(n)
	if n % 2 == 0:
		res = False
	else:
		i = 3
		while i<sq:
			if n % i == 0:
				res = False
				break
			i += 2
	return res
def is_palindrom(n):
	str_num = str(n)
	str_num_rev = str_num[::-1]
	if str_num == str_num_rev:
		return True
	else:
		return False
N = int (raw_input())
if N%2 == 0:
	N += 1
j = N
while N>0:
	if is_prime(j) and is_palindrom(j):
		print j
		break
	j += 2