def main():
    def xor(x, y):
        ans = x ^ y
        return ans
    
    inp1 = list(map(int, input().split()))
    fib = [inp1[0], inp1[1]]
    
    for i in range(inp1[2]):
        front = fib[i] ^ fib[i + 1]
        fib.append(front)
    
    print(fib[inp1[2]])    


if __name__ == '__main__':
    main()