import strutils, sequtils, math

proc tBin(i: int): string =
  var bf = i
  var w = ""
  while bf != 0:
    w = int(bf mod 2 != 0).repr & w
    bf = bf div 2
  result = w

proc xOR0(x0: string, y0: string): string =
  var x, y: string
  y = align(y0, max(x0.len, y0.len), '0')
  x = align(x0, max(x0.len, y0.len), '0')

  result = ""
  for i in 0 ..< x.len:
    if ($x[i]).parseInt + ($y[i]).parseInt == 1:
      result.add('1')
    else:
      result.add('0')

proc rpr(s: string): int =
  for i, v in s:
    if $v == $1:
      result += 2 ^ (s.high - i)


let ris = stdin.readLine.split.map(parseInt)
let (f0, f1, n) = (ris[0], ris[1], ris[2])
let f2 = xOR0(f0.tBin, f1.tBin).rpr

case n mod 3:
of 0: echo f0
of 1: echo f1
of 2: echo f2
else: discard