#if !__INCLUDE_LEVEL__

#include __FILE__
int main()
{
    ll P,Q,R,K;cin >> P >> Q >> R >> K;
    K-=1;
    ll X = 100*(R%10) + 10*(Q%10) + P%10;
    //cout << X << endl;
    int M = 1010;
    int logK = 1;
    while ((1LL << logK) <= K) logK++;
    //ステップ数K,状態数M,初期値X
    // doubling[k][i]:i番目から2^k 進んだ先
    // dsum[k][i]:iから[0~2^k)までの状態の和
    vector<vector<int> > doubling(logK, vector<int>(M));
    vector<vl> dsum(logK, vl(M));
    for (int i = 0; i < M; i++){
        int r = 0;
        int I = i;
        rep(n,3){
            r+=I%10;
            I/=10;
        }
        r%=10;
        doubling[0][i] = r*100+i/10;
    }
    
    //前処理 doubling の計算
    for (int k = 0; k < logK - 1; k++) {
        for (int i = 0; i < M; i++) {
            doubling[k + 1][i] = doubling[k][doubling[k][i]];
        }
    }
    //cout << doubling[0][X] << endl;
    //cout << doubling[1][X] << endl;
    // now…状態
    // sum…今までの状態の和
    int now = X;
    ll sum = 0;
    for (int k = 0; K > 0; k++) {
        if (K & 1) {
            now = doubling[k][now];
        }
        K = K >> 1;
    }
    cout << now%10 << endl;
}

#else

#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i, n) for(int i = 0; i < n; i++)
#define rrep(i, n) for(int i = n-1; i >= 0; i--)
#define range(i, m, n) for(int i = m; i < n; i++)
#define fore(i,a) for(auto &i:a)
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define Sum(v) accumulate(all(v),ll(0))
#define minv(v) *min_element(all(v))
#define maxv(v) *max_element(all(v))
typedef long long ll;
typedef vector<ll> vl;
typedef vector<vector<ll>> vvl;
const ll INF = 1e16;
const ll MOD1 = 1000000007;
const ll MOD2 = 998244353;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
ll SN(char s){return ll(s-'0');}
ll SN(string s){return stoll(s);}
int alpN(char s){return int(s-'a');}
int AlpN(char s){return int(s-'A');}
using Graph = vector<vector<ll>>;
using GraphCost = vector<vector<pair<ll,ll>>>;
using mint = modint;
using mint1 = modint1000000007;
using mint2 = modint998244353;
using pll = pair<long long, long long>;
template <class T>ostream &operator<<(ostream &o,const vector<T>&v){for(int i=0;i<(int)v.size();i++)o<<(i>0?" ":"")<<v[i];return o;}//vector空白区切り出力
ostream& operator<<(ostream& os, const mint1& N) {return os << N.val();}//mint出力。デフォはmint1
ostream& operator<<(ostream& os, const mint2& N) {return os << N.val();}
template<class T> bool contain(const std::string& s, const T& v) {
    return s.find(v) != std::string::npos;
}
ll max(int x,ll y){return max((ll)x,y);}
ll max(ll x,int y){return max(x,(ll)y);}
ll min(int x,ll y){return min((ll)x,y);}
ll min(ll x,int y){return min(x,(ll)y);}
template <typename T>
struct edge {
    int src, to;
    T cost;
    edge(int to, T cost) : src(-1), to(to), cost(cost) {}
    edge(int src, int to, T cost) : src(src), to(to), cost(cost) {}
    edge& operator=(const int& x) {
        to = x;
        return *this;
    }
    operator int() const { return to; }
};

template <typename T>
using Edges = vector<edge<T> >;
template <typename T>
using WeightedGraph = vector<Edges<T> >;
using UnWeightedGraph = vector<vector<int> >;
template <typename T>
using Matrix = vector<vector<T> >;
#endif