package main

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

// 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
}

// replaceAtIndex replaces a character in a string at index i
func replaceAtIndex(in string, r rune, i int) string {
	out := []rune(in)
	out[i] = r
	return string(out)
}