#!/usr/bin/env python3
"""Check if a number is prime."""

def is_prime(n: int) -> bool:
    """Return True if n is a prime number, False otherwise."""
    if n < 2:
        return False
    if n == 2:
        return True
    if n % 2 == 0:
        return False
    for i in range(3, int(n**0.5) + 1, 2):
        if n % i == 0:
            return False
    return True

if __name__ == "__main__":
    import sys
    if len(sys.argv) != 2:
        print("Usage: python prime_checker.py <number>")
        sys.exit(1)
    try:
        num = int(sys.argv[1])
        result = is_prime(num)
        print(f"{num} is {'prime' if result else 'not prime'}")
        sys.exit(0 if result else 1)
    except ValueError:
        print("Please provide a valid integer")
        sys.exit(1)