#include <bits/stdc++.h>

using namespace std;
#define rep(i,n) for (int i = 0; i < (int)(n); ++i)
#define Rep(i,a,b) for (int i = a; i < b; ++i)
#define rRep(i,a,b) for (int i = a; i > b; --i)
#define fore(i,a) for(auto &i:a)
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define Unique(v) v.erase(unique(v.begin(), v.end()), v.end());
#define Bit(x,i) (((x)>>(i))&1)
#define fi first
#define se second
using ll = long long;
using vi = vector<int>;
using vll = vector<long long>;
using vvi = vector<vi>;
using vvll = vector<vll>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template<class T, size_t n, size_t idx = 0> auto mvec(const size_t (&d)[n], const T& init) noexcept { if constexpr (idx < n) return std::vector(d[idx], mvec<T, n, idx + 1>(d, init)); else return init; }
template<class T, size_t n> auto mvec(const size_t (&d)[n]) noexcept { return mvec(d, T{}); }
void print(){ cout << '\n'; }
template<class T, class... Ts> void print(const T& a, const Ts&... b){ cout << a; (cout << ... << (cout << ' ', b)); cout << '\n'; }
template<class... T> constexpr auto Min(T... a){ return min(initializer_list<common_type_t<T...>>{a...}); }
template<class... T> constexpr auto Max(T... a){ return max(initializer_list<common_type_t<T...>>{a...}); }
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
struct settings{ settings(){ ios_base::sync_with_stdio(0); cin.tie(0); cout<<fixed<<setprecision(15); }; }settingss;
const double PI = acos(-1);
const int INF = 1001001001;
const ll LINF = 1001001001001001001LL;

const int mod = 10;
class modint {
  long long x;
public:
  modint(long long x=0) : x((x%mod+mod)%mod) {}
  modint operator-() const {
    return modint(-x);
  }
  modint& operator+=(const modint& a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  modint& operator-=(const modint& a) {
    if ((x += mod-a.x) >= mod) x -= mod;
    return *this;
  }
  modint& operator*=(const  modint& a) {
    (x *= a.x) %= mod;
    return *this;
  }
  modint operator+(const modint& a) const {
    modint res(*this);
    return res+=a;
  }
  modint operator-(const modint& a) const {
    modint res(*this);
    return res-=a;
  }
  modint operator*(const modint& a) const {
    modint res(*this);
    return res*=a;
  }
  modint pow(ll t) const {
    if (!t) return 1;
    modint a = pow(t>>1);
    a *= a;
    if (t&1) a *= *this;
    return a;
  }
  modint inv() const {
    return pow(mod-2);
  }
  modint& operator/=(const modint& a) {
    return (*this) *= a.inv();
  }
  modint operator/(const modint& a) const {
    modint res(*this);
    return res/=a;
  }
  friend ostream& operator<<(ostream& os, const modint& m){
    os << m.x;
    return os;
  }
};

using mat = vector<vector<modint>>;
using vec = vector<modint>;

mat dot(mat &A, mat &B) {
  mat ret(A.size(), vec(B[0].size()));
    for(int i = 0; i < (int)A.size(); ++i) {
      for(int k = 0; k < (int)B.size(); ++k) {
        for(int j = 0; j < (int)B[0].size(); ++j) {
          ret[i][j] = ret[i][j] + A[i][k] * B[k][j];
        }
      }
    }
  return ret;
}

mat mat_pow(mat A, long long n) {
  mat res(A.size(), vec(A.size()));
  for(int i = 0; i < (int)A.size(); i++) {
    res[i][i] = 1;
  }
  while(n > 0) {
    if(n & 1) res = dot(A, res);
    A = dot(A, A);
    n >>= 1;
  }
  return res;
}

int main() {
  ll p, q, r, K; cin >> p >> q >> r >> K;
  p %= 10;
  q %= 10;
  r %= 10;
  mat A = {{1, 1, 1}, {1, 0, 0}, {0, 1, 0}};
  A = mat_pow(A, K-3);
  modint ans = A[0][0] * r + A[0][1] * q + A[0][2] * p;
  cout << ans << endl;
}