import math
def is_simple(n):
    if( n%2 == 0):
        return False
    i = 3
    k =math.sqrt(n)
    while n%i != 0 and i <= k:
        i = i+2
    return n%i != 0


def is_polyndrom(n):
    a = []
    while n > 0:
        d = n%10
        n = int(n/10)
        a.append(d)
    return a[::1] == a[::-1]

n = int(input())

while is_polyndrom(n) == False or is_simple(n)==False:
    n=n+1
print(n)