#include "bits/stdc++.h"
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/tag_and_trait.hpp>
using namespace __gnu_pbds;
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
#define rep(i, m, n) for (ll i = (ll)m; i < (ll)n; i++)
#define drep(i, m, n) for (ll i = m - 1; i >= n; i--)
#define Endl endl
#define all(a) a.begin(), a.end()
#define pr(i, j) make_pair(i, j)
#define isin(x, l, r) (l <= x && x < r)
#define chmin(a, b) a = min(a, b)
#define chmax(a, b) a = max(a, b)
#define srt(ar) sort(ar.begin(), ar.end())
#define rev(ar) reverse(ar.begin(), ar.end())
#define jge(f, s, t) cout << (f ? s : t) << endl
template <typename T>
using ordered_set = tree<T, null_type, std::less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

#define printar(ar)             \
    do                          \
    {                           \
        for (auto dbg : ar)     \
        {                       \
            cout << dbg << " "; \
        }                       \
        cout << endl;           \
    } while (0)
const ll inf = 1e18;
const ld pi = 3.14159265358979;
const ld eps = 1e-9;
template <class T, ll n, ll idx = 0>
auto make_vec(const ll (&d)[n], const T &init) noexcept
{
    if constexpr (idx < n)
        return std::vector(d[idx], make_vec<T, n, idx + 1>(d, init));
    else
        return init;
}

template <class T, ll n>
auto make_vec(const ll (&d)[n]) noexcept
{
    return make_vec(d, T{});
}
//////////////// 以下を貼る ////////////////
template <class T>
size_t HashCombine(const size_t seed, const T &v)
{
    return seed ^ (std::hash<T>()(v) + 0x9e3779b9 + (seed << 6) + (seed >> 2));
}
/* pair用 */
template <class T, class S>
struct std::hash<std::pair<T, S>>
{
    size_t operator()(const std::pair<T, S> &keyval) const noexcept
    {
        return HashCombine(std::hash<T>()(keyval.first), keyval.second);
    }
};
/* vector用 */
template <class T>
struct std::hash<std::vector<T>>
{
    size_t operator()(const std::vector<T> &keyval) const noexcept
    {
        size_t s = 0;
        for (auto &&v : keyval)
            s = HashCombine(s, v);
        return s;
    }
};
/* tuple用 */
template <int N>
struct HashTupleCore
{
    template <class Tuple>
    size_t operator()(const Tuple &keyval) const noexcept
    {
        size_t s = HashTupleCore<N - 1>()(keyval);
        return HashCombine(s, std::get<N - 1>(keyval));
    }
};
template <>
struct HashTupleCore<0>
{
    template <class Tuple>
    size_t operator()(const Tuple &keyval) const noexcept { return 0; }
};
template <class... Args>
struct std::hash<std::tuple<Args...>>
{
    size_t operator()(const tuple<Args...> &keyval) const noexcept
    {
        return HashTupleCore<tuple_size<tuple<Args...>>::value>()(keyval);
    }
};
////////////////////////////////////////////
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    ll a, b, n;
    cin >> a >> b >> n;
    ll x = a ^ b;
    vector<ll> ar = {a, b, x};
    cout << ar[n % 3] << Endl;
}