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
a=raw_input()
def prime(n):
    y=True
    for i in xrange(2,n):
        if n%i==0:
            y=False
            break
    return y        
z=False 
i=a           
while  not z:

    
    if i==i[::-1] and prime(int(i))==True:
        z=True
        print i
    else:
         i=str(int(i)+1)