# This program computes the nth Fibonacci number
def fibI(n):
    if n <= 1: return n
    else:
       f0, f1 = 0, 1
       for i in range(2,n+1):
           f0, f1 = f1, f0+f1
       return f1

def fibR(n):
    if n <= 1: return n
    return fibR(n-1) + fibR(n-2)

def fibRE(n, f0,  f1):
    if n == 0: return f0
    if n == 1: return f1
    else: return fibRE(n-1, f1, f0+f1)
  
def main(): 
    n = input("Enter a non -ve integer: ")
    print "Fib(", n, ") =", fibI(n)
    print "Fib(", n, ") =", fibRE(n, 0, 1)
    print "Fib(", n, ") =", fibR(n)
main()