import strutils, sequtils, math

let
  t = stdin.readLine.split.map parseInt
  (x, y, r) = (t[0].abs, t[1].abs, t[2])
  r0 = (x ^ 2 + y ^ 2).float.sqrt

  p1 = r0 + r.float * (2.0).sqrt


if r0 != 0.0:
  let
    ang = arccos(x.float / r0)
    p2 = (r0 + r.float) * (ang.sin + ang.cos)

  echo max(p1, p2).ceil.int

else:
  echo p1.ceil.int