import argparse

parser = argparse.ArgumentParser()
parser.add_argument('-f', '--file', required=True,
                    help="input file to be sorted")
parser.add_argument('-u', '--unique', action='store_true',
                    help="sort uniquely")
args = parser.parse_args()

ip_lines = open(args.file).readlines()
if args.unique:
    ip_lines = set(ip_lines)

op_lines = sorted(ip_lines, key=lambda s: (s.rsplit('.', 1)[-1], s))
for line in op_lines:
    print(line, end='')