import java.util.Scanner

object Problem011 {

  def proc(markKinds: Int, suitKinds: Int, handNum: Int, hand: Seq[(Int, Int)]): Long = {
    val handMarkNum = hand.map(x => x._1).distinct.size
    val handSuitNum = hand.map(x => x._2).distinct.size

    val matchCount: Long = handMarkNum * suitKinds + handSuitNum * markKinds
    val doubleCount: Long = handMarkNum * handSuitNum

    matchCount - doubleCount - handNum
  }

  def main(args: Array[String]) = {
    val sc = new Scanner(System.in)
    val w = sc.nextInt()
    val h = sc.nextInt()
    val n = sc.nextInt()
    val sk: Seq[(Int, Int)] = Seq.fill(n)(sc.nextInt(), sc.nextInt())

    val result = proc(w, h, n, sk)
    println(result)
  }
}