#include<bits/stdc++.h>
#define L(i, j, k) for(int i = (j); i <= (k); ++i)
#define R(i, j, k) for(int i = (j); i >= (k); --i)
#define ll long long 
#define sz(a) ((int) (a).size())
#define pb emplace_back
#define me(a, x) memset(a, x, sizeof(a))
#define vi vector<int>
#define ull unsigned long long
#define i128 __int128
#define double long double
using namespace std;
#define pii pair<int,int>
const int N = 1 << 21;
const int mod = 998244353;
ll a, b, c, n;
ll f[N];
int main() {
	// int P = 768;
	// L(i, 2, P) while(P % i == 0) {
	// 	P /= i;
	// 	cout << i << endl;
	// }
	// return 0;
	ios :: sync_with_stdio(false);
	cin.tie(0); cout.tie(0);
	cin >> a >> b >> c >> n;
	if(n == 1) {
		cout << a << '\n';
		return 0;
	}
	if(n == 2) {
		cout << b << '\n';
		return 0;
	}
	n -= 3;
	int hb = 1;
	while((1 << hb) <= max(max(a, b), c))++hb;
	ll cyc = (1LL << (hb - 1)) * 3;
	ll x = a, y = b;
	vector<ll>inc;
	L(i, 0, cyc - 1) {
		f[i] = x ^ y;
		f[i] += c;
		if(f[i] >> hb & 1) f[i] -= 1 << hb, inc.pb(i);
		x = y, y = f[i];
	}
	int ans = f[n % cyc];
	int mut = 1LL << hb;
	while(sz(inc)) {
		// cout << "SZ = " << sz(inc) << ' ' << inc[0] << ' ' << cyc << endl;
		vector<ll>pub;
		int len = sz(inc);
		inc.resize(len * 2);
		L(i, 0, len - 1) {
			inc[i + len] = inc[i] + cyc;
		}
		if(cyc <= n) cyc *= 2;
		ll curt = 0, X = 0, Y = 0;
		auto work = [&] (ll t) {
			L(j, 1, t % 3) {
				Y ^= X;
				X ^= Y;
			}
			return;
		};
		ll P = n % cyc;
		int eval = -1;
		for(auto&u : inc) {
			if(curt <= P && P < u) {
				work(P - curt);
				eval = X ^ Y;
				work(u - P);
			} else {
				work(u - curt);
			}
			if(X ^ Y) pub.pb(u);
			Y ^= X;
			X ^= Y;
			Y ^= 1;
			if(P == u) {
				eval = Y;
			}
			curt = u + 1;
		}
		if(curt <= P) {
			work(P - curt);
			eval = X ^ Y;
		}
		if(eval) (ans += mut) %= mod;
		// cout << "eval="<<eval<<endl;
		mut = (ll)mut * 2 % mod;
		inc = pub;
		while(sz(inc) && inc.back() > n) inc.pop_back();
	}
	cout << ans << '\n';
	return 0;
}