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(a):
    if (a!=2 and a%2==0) or a==1:
        return False
    else:
        for i in range(3,a/2):
            if a%i==0:
                return False
        return True
        
def ispalindrome(a):
    return a==a[::-1]
    
N=int(raw_input())
while True:
    if ispalindrome(str(N)):
        if isprime(N):
            print(N)
            break
    N+=1