#include<bits/stdc++.h>
using namespace std;
constexpr int mod=998244353;
typedef unsigned long long ll;
main(){
    int a,b,c;ll n;cin>>a>>b>>c>>n;
    if(n<=2)return cout<<(n==1?a:b)<<'\n',0;n-=3;
    int mx=1<<1+__lg(max({a,b,c}));ll z=3*mx,ans=0;
    vector<ll> B;
    for(int i=0,pos=n%z,w=mx*2-1;i<z;i++){
        swap(a,b);b=(b^a)+c;
        if(i<=n&&b>w)B.emplace_back(i);b&=w;
        if(i==pos)ans=b;
    }
    while(!B.empty()){
        vector<ll> tmp;
        bool cur=0,a[3]={0,0,0},cnm=0;
        ll pos=n%(z<<1);
        int nn=B.size();for(int i=0;i<nn;i++)B.emplace_back(B[i]+z);
        for(ll x:B){
            if(x>n) break;
            if(!cnm&&pos<x)cur=a[pos%3],cnm=1;
            if(a[x%3]) tmp.emplace_back(x);
            a[x%3]^=true;a[(x+1)%3]^=true;
        }
        if(z<=n)z<<=1;
        mx<<=1;if(mx>=mod)mx-=mod;
        if(!cnm) cur=a[pos%3];
        if(cur) ans+=mx;
        swap(B,tmp);
    }
    cout<<ans%mod<<'\n';
}