let i = require('fs').readFileSync('/dev/stdin', 'utf8').split('\n')
let w = parseInt(i[0])
let h = parseInt(i[1])
let m = []
let n = []
let r = 0
for (let c = 3; c < i.length - 1; c++) {
  let sk = i[c].split(' ').map((e) => parseInt(e))
  let b1 = b2 = true
  if (m.indexOf(sk[0]) == -1) m.push(sk[0])
  else b2 = false
  if (n.indexOf(sk[1]) == -1) n.push(sk[1])
  else b1 = false
  if (b1) r += w - m.length
  else r -= 1
  if (b2) r += h - n.length
  else r -= 1
}
console.log(r)