text: from math import sqrt, ceil
  
  
  def isPrime(x):
      """Primality test.
  
      Param x: int.
  
      Returns True if x is prime, False otherwise.
      """
      if x <= 0:
          return False
      elif x == 2 or x == 3:
          return True
      else:
          for i in range(2, ceil(sqrt(x)) + 1):
              if x % i == 0:
                  return False
          return True
  
  
  if __name__ == "__main__":
      strNum = input("Enter number to check if prime (-1 to quit): ")
      while strNum != '-1':
          num = int(strNum)
          print(isPrime(num))
          strNum = input("Enter number to check if prime (-1 to quit): ")
  