import math

def is_prime(num):
    if num <= 1:
        return False
    if num == 2 or num == 3:
        return True
    if num % 2 == 0 or num % 3 == 0:
        return False
    i = 5
    while i * i <= num:
        if num % i == 0 or num % (i + 2) == 0:
            return False
        i += 6
    return True

def find_largest_prime_less_than_or_equal_to(n):
   
    largest_prime = 0
    for i in range(n, 1, -1):
        if is_prime(i):
            largest_prime = i
            break
    return largest_prime


def find_twin_primes_less_than_or_equal_to(largest_prime):
    twin_primes = []
    for i in range(2, largest_prime - 1):
        if is_prime(i) and is_prime(i + 2):
            twin_primes.append((i, i + 2))
    return twin_primes

number = int(input(": "))


if is_prime(number):
    print(f"{number} ")
else:
    print(f"{number} .")
  end
}