package main

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

var sum int

func main() {
	in := bufio.NewScanner(os.Stdin)
	for in.Scan() {
		sum += diff(in.Text())
	}
	fmt.Println(sum)
}

func diff(l string) int {
	var min, max int
	for n, s := range strings.Split(l, "\t") {
		i, _ := strconv.Atoi(s)
		if n == 0 {
			min = i
			max = i
		} else {
			if min > i {
				min = i
			}
			if max < i {
				max = i
			}
		}
	}
	return max - min
}