class Yukicoder
  def initialize
    w = gets.to_i
    h = gets.to_i
    n = gets.to_i

    marks = Array.new(w){ Array.new(h, 0)}
    nums = Hash.new(0)
    check_list = Hash.new(false)

    n.times do
      s, k = gets.chomp.split.map{|i| i.to_i-1}

      if !check_list[s]
        marks[s] = Array.new(h, 1)
        check_list[s] = true
      end

      nums[k] = 1
    end

    answer = 0

    marks.each do |mark|
      num = 0

      mark.each_with_index do |n, i|
        num += [n, nums[i]].max
      end

      answer += num
    end

    puts answer - n
  end
end

Yukicoder.new