package two

import (
	"bufio"
	"io"
	"strconv"
	"strings"
)

func parseLines(r io.Reader) ([]int, error) {
	secrets := []int{}

	scanner := bufio.NewScanner(r)
	for scanner.Scan() {
		secrets = append(secrets, mustConv(strings.TrimSpace(scanner.Text())))
	}

	if err := scanner.Err(); err != nil {
		return nil, err
	}

	return secrets, nil
}

func mustConv(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		panic(err)
	}
	return n
}

func lastDigit(n int) int {
	return n % 10
}