w = gets.to_i
h = gets.to_i
n = gets.to_i
t = []
n.times do 
  t.push(gets.chomp.split(" ").map(&:to_i))
end
tt = Array.new(w)
tt.fill(0)
t.map{|u|u[0]}.each do |d|
  tt[d-1] += 1
end 
a = 0
m = []
mm = []
w.times do |d|
  unless(tt[d] == 0)
    p = h - tt[d]
    a += p 
    m.push(d)
    mm.push(t.map{|u|u[1]})
  end 
end
m.uniq!
mm = mm.flatten.uniq
a += mm.size * (w - m.size) 
p a