import java.io.BufferedReader; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.Comparator; import java.util.LinkedList; import java.util.List; import java.util.Queue; public class Main { public static boolean result[]; public static int dp[][]; public static void main(String[] args) throws NumberFormatException, IOException{ ContestScanner in = new ContestScanner(); long[] f = new long[3]; f[0] = in.nextLong(); f[1] = in.nextLong(); f[2] = f[0]^f[1]; System.out.println(f[(int)(in.nextLong()%3)]); } } class MyComp implements Comparator{ public int compare(int[] a, int[] b) { return a[0] - b[0]; } } class Reverse implements Comparator{ public int compare(Integer arg0, Integer arg1) { return arg1 - arg0; } } class Node{ int id; List edge = new ArrayList(); public Node(int id){ this.id = id; } public void createEdge(Node node){ edge.add(node); } } class ContestScanner{ private BufferedReader reader; private String[] line; private int idx; public ContestScanner() throws FileNotFoundException{ reader = new BufferedReader(new InputStreamReader(System.in)); } public ContestScanner(String filename) throws FileNotFoundException{ reader = new BufferedReader(new InputStreamReader(new FileInputStream(filename))); } public String nextToken() throws IOException{ if(line == null || line.length <= idx){ line = reader.readLine().trim().split(" "); idx = 0; } return line[idx++]; } public long nextLong() throws IOException, NumberFormatException{ return Long.parseLong(nextToken()); } public int nextInt() throws NumberFormatException, IOException{ return (int)nextLong(); } public double nextDouble() throws NumberFormatException, IOException{ return Double.parseDouble(nextToken()); } }