package main

import (
	"bufio"
	"flag"
	"fmt"
	"os"
)

func main() {
	lines := flag.Int("n", 10, "Lines")
	reverse := flag.Bool("r", false, "Reverse")
	flag.Parse()
	args := flag.Args()

	// 引数があるか確認
	if len(args) == 0 {
		fmt.Println("Plese input file path.")
		os.Exit(1)
	}

	file, err := os.Open(args[0])
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
	defer file.Close()

	var text []string

	sc := bufio.NewScanner(file)
	// linesNumber := *lines + 1

	for i := 1; sc.Scan(); i++ {
		text = append(text, sc.Text())
	}

	for i := 0; i < *lines; i++ {
		if len(text) > i {
			if *reverse {
				point := len(text) - 1 - i
				fmt.Println(text[point])
			} else {
				fmt.Println(text[i])
			}
		}
	}
}