import java.util.Scanner; public class Main_yukicoder64 { public static void main(String[] args) { Scanner sc = new Scanner(System.in); long[] f = new long[3]; f[0] = sc.nextLong(); f[1] = sc.nextLong(); f[2] = f[0] ^ f[1]; long n = sc.nextLong(); System.out.println(f[(int)(n % 3)]); sc.close(); } }