# ShowPS.py
# Name:
# Date:
""" Illustrates the perfect shuffle permutation
and examines how many are required before
returning to the original list.
"""

def PS(x):
    pass
        
def numPS(n):
    pass
    
if __name__ == '__main__':
    n = input('Enter an even integer: ')
    print '\nnumPS(%1d) = %1d' % (n,numPS(n))
    if n<=20:
        a = [i for i in range(10,10+n)]
        print '\na ='
        print a
        PS(a)
        print '\nPS(a) ='
        print a