#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (int)n; i++)
using ll = long long;
using vec = vector<ll>;
using mat = vector<vec>;
constexpr ll mod = 10;

mat mul(mat& A, mat& B){
  mat C(A.size(), vec(B[0].size(),0));
  rep(i, A.size()){
    rep(j, B[0].size()){
      rep(k, A[0].size()){
        C[i][j] = (C[i][j] + A[i][k]*B[k][j]) % mod;
      }
    }
  }
  return C;
}

mat pow(mat& A, ll n) {
  mat B(A.size(), vec(A.size(), 0));
  rep(i, A.size()) B[i][i] = 1;
  while(n > 0){
    if(n & 1) B = mul(B, A);
    A = mul(A, A);
    n >>= 1;
  }
  return B;
}

int main(){
  ll p, q, r, k;
  cin >> p >> q >> r >> k;
  mat A(3,vec(3));
  A[0][0] = 1; A[0][1] = 1; A[0][2] = 1;
  A[1][0] = 1; A[1][1] = 0; A[1][2] = 0;
  A[2][0] = 0; A[2][1] = 1; A[2][2] = 0;
  A = pow(A,k-3);
  ll ans = (A[0][0]*r+A[0][1]*q+A[0][2]*p) % mod;
  cout << ans << endl;
  return 0;
}