#!/opt/local/bin/python # # See ../README.md # # # Run as: python ch-1.py < input-file # import fileinput def make_sequence (string, start): if string == start: return [start] if 0 == string . find (start): tail = string [len (start) :] result = make_sequence (tail, str (int (start) + 1)) or \ make_sequence (tail, str (int (start) - 1)) if result: return [start] + result return None for line in fileinput . input (): line = line . strip () for i in range (0, len (line)): result = make_sequence (line, line [0 : i + 1]) if result: print ("," . join (result)) break