package main

import (
    "fmt"
    "os"
    "strings"
    "strconv"
    "sort"
)

func check(e error) {
    if e != nil {
        panic(e)
    }
}

func abs(n int) int {
	if n < 0 {
		return -n
	}
	return n
}

func main() {
    // read in file as lines
    dat, err := os.ReadFile("data.txt")
    check(err)
    
    lines := strings.Split(string(dat), "\n")

    // construct lists
    left_list := []int{}
    right_list := []int{}

    for i := range len(lines) - 1 {
        numbers := strings.Split(lines[i], "   ")

        left_num, err := strconv.Atoi(numbers[0])
        check(err)
        right_num, err := strconv.Atoi(numbers[1])
        check(err)

        left_list = append(left_list, left_num)
        right_list = append(right_list, right_num)
    }
    
    // sort lists
    sort.Ints(left_list)
    sort.Ints(right_list)

    // count difference
    distance := 0
    for i := range left_list {
        distance += abs(left_list[i] - right_list[i])
    }

    fmt.Println(distance)
}