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 prime(x):
    if x == 1: 
        return False
    if x == 2 or x == 3: 
        return True
    if x % 2 == 0: 
        return False
    for i in range(3, int(x ** 0.5)):
        if x % i == 0:
            return False 
    return True
        
def palindrome(n):
    return n==n[::-1]
    
N=int(input())
while True:
    if palindrome(str(N)):
        if prime(N):
            print(N)
            break
    N+=1