#!/usr/bin/env python3

import sys
import contextlib
import fileinput
from typing import Set


def main() -> None:
    seen: Set[str] = set()
    for line in fileinput.input(encoding="utf-8", mode="r"):  # type: ignore
        lowered = line.lower()
        if lowered in seen:
            continue
        seen.add(lowered)
        sys.stdout.write(line)
    sys.stdout.flush()


if __name__ == "__main__":
    with contextlib.suppress(KeyboardInterrupt):
        main()