#!/usr/bin/env ruby

def manhattan_distance(x, y, p)
  return (x - p.first).abs + (y - p.last).abs
end

input = $stdin.readlines.map(&:chomp).map{|i|i.split(", ").map(&:to_i)}
MAX_DISTANCE = 10000

xoff = input.map(&:first).min - 1
yoff = input.map(&:last).min - 1

input.each do |p|
  p[0] -= xoff
  p[1] -= yoff
end

wid = input.map(&:first).max + 1
hei = input.map(&:last).max + 1

grid = Array.new(wid) { Array.new(hei, false) }

(0...wid).each do |x|
  (0...hei).each do |y|
    dist_sum = input.map{|p|manhattan_distance(x, y, p)}.sum
    grid[x][y] = true if dist_sum < MAX_DISTANCE
  end
end

puts grid.flatten.count(true)