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
read = lambda: map(int, raw_input().split())
read_s = lambda: map(str, raw_input().split())

def is_pali(n):
    return str(n) == ''.join(reversed(str(n)))

def is_prime(n):
    import math
    for i in range(2, int(math.sqrt(n) + 1)):
        if n % i == 0:
            return False
    return True

n, = read()
while True:
    if is_pali(n):
        if is_prime(n):
            print n
            break
    n += 1