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==0:
		return False
	else:
		s = int(pow(n,0.5))
		for i in range(2,s+1):
		    if n%i==0:
				return False
	return True
	
def isPalindrome(n):
	s = str(n)
	return s==s[::-1]
	
N = int(raw_input())
if N%2 == 0:
   N = N+1
while not (isPalindrome(N) and isPrime(N)):
	N = N+2
print N