#include <stdio.h>
#include <stdlib.h>

int main(void) {
  long a, b, c, d;

  scanf("%ld %ld %ld", &a, &b, &c);
  switch (c % 3){
    case 0:
      d = a;
      break;
    case 1:
      d = b;
      break;
    default:
      d = a ^b;
      break;
  }
  printf("%ld\n", d);

  return EXIT_SUCCESS;
}