import strutils, sequtils, math

let
  t = stdin.readLine.split.map parseInt
  (x, y, r) = (t[0], t[1], t[2])

  r0 = (x ^ 2 + y ^ 2).float.sqrt
  dis = r0 + r.float


if r0 != 0.0:
  let ang = arccos(x.float / r0)
  echo (dis * (ang.sin.abs + ang.cos.abs)).ceil.int
else:
  echo (r.float * (2.0).sqrt).ceil.int