let X = abs(Int(readLine()!)!)
let Y = abs(Int(readLine()!)!)
let L = Int(readLine()!)
var command = 0
command += Y / L!
command += (0 != (Y % L!) ? 1 : 0)
command += (0 != X ? 1 : 0)
command += X / L!
command += (0 != (X % L!) ? 1 : 0)
print(command)