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 pr():
    global N
    for i in xrange(2, N/2):
        if N % i == 0:
            return False
    else:
        return True        

N = int(raw_input())
while True:
    #check for palindrome
    strN = str(N)
    if strN == strN[::-1]:
        if pr():
            print N
            break
        else:
            N += 1
    else:
        N += 1