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

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

  scanf("%ld %ld %ld", &a, &b, &c);

  if (c == 0)
    printf("%ld\n", a);
  else {
    for (i = 1; i < c; i++) {
      d = a ^ b;
      a = b;
      b = d;
    }
    printf("%ld\n", b);
  }

  return EXIT_SUCCESS;
}