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(n):
    t=n**0.5
    for i in range(2,int(t+1)):
        if n%i==0:
            return 0
        else:
            continue
    return 1
def pal(n):
    if str(n)==str(n)[::-1]:
        return 1
    else:
        return 0
a=input()
while True:
    t=pal(a)
    if t==1:
        t1=prime(a)
        if t1==1:
            print a
            break
        else:
            a=a+1
            pass
    else:
        a=a+1