def chicken_rabbit(num_heads, num_legs):
    lowest_num_legs = num_heads * 2 # Lowest possible amount of legs
    difference = num_legs - lowest_num_legs
    num_one = difference / 2
    num_two = num_heads - num_one
    return num_two, num_one


def unittest_function_pass():
    # write assertion statements here to test the function
    # enumerate as many test cases you can think of to test your function
    # See "Additional Requirements described in the assignment" for details.
    listB = []
    listB = chicken_rabbit(31, 94)
    assert(listB[0] > 0)
    return

def unittest_function_xfail():
    # write assertion statements here to test the function on any expected failing cases
    # See "Additional Requirements described in the assignment" for details.
    listA = []
    listA = chicken_rabbit(7, 56)
    assert(listA[0] > 0)
    return

if __name__ == "__main__":
    num_heads = int(input("Input number of heads:\n"))
    num_legs = int(input("Input number of legs:\n"))
    n_chicken, n_rabbit = chicken_rabbit(num_heads, num_legs)
    if (n_chicken < 0 or n_rabbit < 0):
        print("Invalid inputs received. Program aborted.")
    else:
        if n_chicken == 1:
            print("There is 1 chicken in the cage")
        elif n_chicken == 0:
            print("There isn't any chicken in the cage")
        else:
            print("There are %d chickens in the cage" % n_chicken)

        if n_rabbit == 1:
            print("There is 1 rabbit in the cage")
        elif n_rabbit == 0:
            print("There isn't any rabbit in the cage")
        else:
            print("There are %d rabbits in the cage" % n_rabbit)


    # TODO: complete the unittest_function so your function undergo a rigorous unittest created by yourself
    unittest_function_pass()

    # TODO: complete the unittest_function_xfail so your function undergo a rigorous unittest created by yourself
    # Please note that unittest_function_xfail is ALWAYS expected to trip an error! Because it is testing on expected failing cases