#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); i++)
#define REP(i,a,b) for(int i=(a);i<(b);i++)
#define all(v) begin(v),end(v)
#define fi first
#define se second
template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
constexpr ll inf = 2e9;
constexpr ll llinf = 9e18;
//constexpr ll MOD = 998244353;
constexpr ll MOD = 1000000007;
const double pai=acos(-1);

int main() {
    //cout<<fixed<<setprecision(15);
    ll a,b,n;cin>>a>>b>>n;
    if(n==0)cout<<a<<endl;
    else if(n==1)cout<<b<<endl;
    else if(n==2)cout<<(a^b)<<endl;
    else {
        ll ans=a^b;
        if(n%2==0)ans^=a;
        else ans^=b;
        cout<<ans<<endl;
    }
}