X, Y, L = [gets, gets, gets].map(&:to_i)

order_count = 0
unless X.zero?
  div, mod = X.divmod(L)
  order_count += (div.abs + (mod.zero? ? 1 : 2))
end

unless Y.zero?
  div, mod = Y.divmod(L)
  order_count += (div.abs + (mod.zero? ? 0 : 1))
end

puts order_count