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
n=raw_input()
t=False
 
def is_prime(i):
    for x in range(2,int(i**.5)):
        if i % x == 0:
            return False
    else:
        return True

while t!=True:
    if str(n)==str(n)[::-1] :
        if is_prime(int(n))==True:
            print n
            t=True
        else:
            n=int(n)+1
    else:
        n=int(n)+1