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
isPrime=lambda x: all(x % i != 0 for i in range(int(x**0.5)+1)[2:])
def ispal(x):
    return x == x[::-1]
n = int(raw_input())
if not n % 2: n += 1
if n > 98689:
    print 1003001
else:    
    for i in range(n, 100000, 2):
        if isPrime(i) and ispal(str(i)):
            print i
            break