package main

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

var sc = bufio.NewScanner(os.Stdin)
var rdr = bufio.NewReaderSize(os.Stdin, 1000000)

func main() {
	sc.Split(bufio.ScanWords)
	w, h, n := nextInt64(), nextInt64(), nextInt64()
	ws := make(map[int64][]int64)
	hs := make(map[int64]int64)
	t := int64(0)
	for i := int64(0); i < n; i++ {
		s, k := nextInt64(), nextInt64()
		ws[s] = append(ws[s], k)
		hs[k]++
	}

	for _, v := range ws {
		t += h - int64(len(v))
	}

	for k, v := range hs {
		t += w - v
		for _, s := range ws {
			in := false
			for _, v2 := range s {
				if k == v2 {
					in = true
					break
				}
			}
			if in {
				continue
			}
			t--
		}
	}
	fmt.Println(t)
}

func nextLine() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	i, _ := strconv.Atoi(nextLine())
	return i
}

func nextInt64() int64 {
	i, _ := strconv.ParseInt(nextLine(), 10, 64)
	return i
}