package main

import (
	"bufio"
	"log"
	"os"
	"strconv"
)

// readlines reads lines from stdin.
// it returns them as an array of strings
func readlines() []string {
	lines := []string{}

	scanner := bufio.NewScanner(os.Stdin)
	for scanner.Scan() {
		lines = append(lines, scanner.Text())
	}

	if err := scanner.Err(); err != nil {
		log.Fatal(err)
	}

	return lines
}

// mustConv converts string to int
// it will panic if an error occurs
func mustConv(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		panic(err)
	}
	return n
}