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? ? 0 : 1))
end

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

order_count += 1 if !X.zero? && !Y.zero?
puts order_count