def Collatz(number , algorithm):
if( number == 1)
    print number,
    return
if(algorithm == 'F'):
    if( number % 2 == 1):
        print number,
        Collatz( (3*number) + 1, algorithm)
    if( number % 2 == 0):
        print number,
        Collatz((number/2),algorithm)
if(algorithm == 'B'):
    if( number % 2 == 1):
        Collatz( (3*number) + 1, algorithm)
        print number,
    if( number % 2 == 0):
        Collatz((number/2),algorithm)
        print number,
**if( algorithm == 'P'):**

m = input( "Enter a positive integer value: " )
displaymode = ''  # initialize to anything not F, B, P
while displaymode not in ['F', 'B', 'P'] :
 displaymode = raw_input( "Choose a display mode:  F=forward, B=backward,   P=palindrome: " )
Collatz( m, displaymode )
print