"""
date:     January 25, 2012
category: conditionals
purpose:  prompt user
"""

age_text = input("Enter your age:  ")
age = int(age_text)

if 0 < age :
    if 0 <= age and age < 20 :
        print("you are young")
    elif 20 <= age and age < 40 :
        print("you are middle-aged")
    elif 40 <= age :
        print("you are old")

    # section 2
    if 0 <= age and age < 20 :
        print("you are young")

    if 20 <= age and age < 40 :
        print("you are middle-aged")

    if 40 <= age :
        print("you are old")

    # section 3
    if 40 <= age :
        print("you are old")
    elif 20 <= age :
        print("you are middle-aged")
    elif 0 <= age :
        print("you are young")
else :
    print("invalid input")