#!/usr/bin/env python3

#!/usr/bin/env python
# -*- coding: utf-8 -*-

# Copyright (c) 2019 Karl Fogel
# 
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
# 
# If you did not receive a copy of the GNU General Public License
# along with this program, see <http://www.gnu.org/licenses/>.

"""Print unique lines from the input, preserving the input's order."""

import sys
import fileinput

def main():
    input_lines = { }  # Since Python 3.7, dicts preserve insertion order.
    for line in fileinput.input():
        input_lines[line] = True
    for line in input_lines:
        sys.stdout.write(line)

if __name__ == '__main__':
  main()