func main()
	var w: int :: cui@inputInt()
	var h: int :: cui@inputInt()
	var n: int :: cui@inputInt()
	var s: []int :: #[n]int
	var k: []int :: #[n]int
	for i(0, n - 1)
		do s[i] :: cui@inputInt()
		do k[i] :: cui@inputInt()
	end for
	var ms: dict<int, bool> :: #dict<int, bool>
	var mk: dict<int, bool> :: #dict<int, bool>
	for i(0, n - 1)
		do ms.add(s[i], true)
		do mk.add(k[i], true)
	end for
	var ns: int :: ^ms
	var nk: int :: ^mk
	
	var ans: int :: ns * nk - n + (w - ns) * nk + (h - nk) * ns
	do cui@print("\{ans}\n")
end func