def prime(n):
    if n <= 1:
        return False
    for i in range(2, int(n**0.5 ) + 1):
        if n % i == 0:
            return False
    return True

while True: 
    try:
        num = int(input("enter a namber :"))
        if num <= 0 :
          raise ValueError
        break
    except ValueError:
        print("Please enter a positive integer.")
        
if prime(num):
    print(f"{num} is a prime number " )
else:
    print(f"{num} is not prime number ")