#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef __int128 i128;
const int K=20;
vector<ll> v1,v2;
ll n;
i128 ans;
int a,b,c,t[3];
int main()
{
	scanf("%d%d%d%lld",&a,&b,&c,&n),n-=3;
	if(n<0) return printf("%d\n",n==-2?a:b),0;
	i128 m=3<<(K-1);
	for(int i=0;i<m;i++)
	{
		int res=(a^b)+c;
		if(res>=(1<<K)&&i<=n) v1.push_back(i),res-=(1<<K);
		a=b,b=res;
		if(n%m==i) ans=res;
	}
	for(int j=K;v1.size();j++)
	{
		for(auto x:v1) v2.push_back(x);
		for(auto x:v1) if(x<=n-m) v2.push_back(x+m);
		v1.clear(),m<<=1;
		ll k=n%m;
		for(int i=0;i<3;i++) t[i]=0;
		for(auto x:v2)
		{
			if(x>k) ans|=((i128)t[k%3])<<j,k=m;
			int res=t[x%3];
			if(res==1) v1.push_back(x);
			t[x%3]^=1,t[(x+1)%3]^=1;
		}
		if(k<m) ans+=((i128)t[k%3])<<j;
		while(v1.size()&&v1.back()>n) v1.pop_back();
		v2.clear();
	}
	printf("%d\n",(int)(ans%998244353));
}