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
def isPrime(n):
	if(n < 2):
		return False
	i = 2
	while(i*i <= n):
		if(n%i == 0):
			return False
		i += 1
	return True

def isPalin(n):
	s = str(n)
	return s==s[::-1]

n = input()
while(True):
	if(isPalin(n)):
		if(isPrime(n)):
			print n
			break
	n += 1