1092B.go

package main

import (
	"bufio"
	. "fmt"
	"io"
	"sort"
)

// github.com/EndlessCheng/codeforces-go
func CF1092B(_r io.Reader, _w io.Writer) {
	in := bufio.NewReader(_r)
	out := bufio.NewWriter(_w)
	defer out.Flush()

	var n, s int
	Fscan(in, &n)
	a := make([]int, n)
	for i := range a {
		Fscan(in, &a[i])
	}
	sort.Ints(a)
	for i := 0; i < n; i += 2 {
		s += a[i+1] - a[i]
	}
	Fprint(out, s)
}

//func main() { CF1092B(os.Stdin, os.Stdout) }