# File:    tuThFib.py
# Author:  Dr. Gibson
# Date:    11/22/2016
# Section: N/A
# E-mail:  k.gibson@umbc.edu 
# Description:
#   This file contains python code that recursively implements
#   the Fibonacci sequence.

FIB_FIRST  = 0
FIB_SECOND = 1
INVALID    = -1

def fib(num):
    # BASE CASES
    if num <= 0:
        return INVALID
    elif num == 1:
        return FIB_FIRST
    elif num == 2:
        return FIB_SECOND

    # RECURSIVE CASE
    else:
        return fib(num - 1) + fib(num - 2)
    
def main():

    num = int(input("What number of the Fibonacci sequence do you want? "))
    ans = fib(num)
    print("The Fibonacci sequence's ", str(num) + "th number is:", ans)


main()