In mathematics, the power set (or powerset) of any set S is the set of all subsets of S, including the empty set and S itself
Take the set S1 = {'1','2'} for example:
the power set of S1 is {{},{'1'},{'2'},{'1','2'}}
00 -> empty set, 01 -> {'1'}, 10 -> {'2'} , 11 -> {'1','2'} (00,01,10,11 is the binary representation of power set's index)
Take the set S2 = {'1','2','3'} for example:
the power set of S2 is {{},{'1'},{'2'},{'1','2'},{'3'},{'1','3'},{'2','3'},{'1','2','3'}}
In this problem, you are asked to generate power set by given a aspecific set.
S
S: the input string can be viewed as a set ( 4 <= S <= 21)
Output the element of power set (followed by a newline character at the end of each output element)