Algoritmo que pida un número y diga si es positivo, negativo o 0 (if, elif, else, …).

def ask_number():
  number = int(input("Introduce a number: "))
  if number < 0:
    print("The number is negative")
  elif number > 0:
    print("The number is positive")
  elif number == 0:
    print("The number is 0")

ask_number()