package main

import (
	"fmt"
)

func main() {
	solve11()
}

func solve11(){
	var W, H, N int
	fmt.Scan(&W, &H, &N)
	var s, k int
	var ans int
	spot := make([]int, W)
	num := make([]int, H)
	for i:=0; i<N; i++ {
	    fmt.Scan(&s, &k)
		s--
		k--
		spot[s]++
		num[k]++
	}
	for i:=0; i<W; i++ {
	    if spot[i]!=0{
			ans += H - spot[i]
		}
	}
	for i:=0; i<H; i++ {
	    if num[i]!=0{
			ans += W - num[i]
		}
	}
	fmt.Println(ans)
	//fmt.Println(spot, num)
}