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 is_prime(a):
    return all(a % i for i in xrange(2, a))
def is_palindrome(n):
	return str(n) == str(n)[::-1]
n=int(raw_input())
if(n==1):
	n=2
elif n>=98690:
    print "1003001"
else:
	for i in range(n,1003001):
		if(is_prime(i) and is_palindrome(i)):
			print i
			break