#include <bits/stdc++.h>
using namespace std;

int main() {
  
  ios::sync_with_stdio(false);
  cin.tie(0);
  
  vector<int> fst(3);
  for (int i=0;i<3;i++) {
    cin >> fst[i];
    fst[i] %= 10;
  }
  long long k;
  cin >> k;
  vector<vector<int>> mat(3,vector<int>(3,0));
  vector<vector<int>> ks(3,vector<int>(3,0));
  for (int i=0;i<3;i++) {
    mat[i][i] = 1;
  }
  ks[0][1] = 1;
  ks[1][2] = 1;
  ks[2][0] = 1;
  ks[2][1] = 1;
  ks[2][2] = 1;
  long long left = k-3;
  while (left > 0) {
    if (left%2 == 1) {
      vector<vector<int>> nmat(3,vector<int>(3));
      for (int i=0;i<3;i++) {
        for (int j=0;j<3;j++) {
          for (int k=0;k<3;k++) {
            nmat[i][j] += mat[i][k]*ks[k][j];
            nmat[i][j] %= 10;
          }
        }
      }
      mat = nmat;
    }
    vector<vector<int>> nks(3,vector<int>(3));
      for (int i=0;i<3;i++) {
        for (int j=0;j<3;j++) {
          for (int k=0;k<3;k++) {
            nks[i][j] += ks[i][k]*ks[k][j];
            nks[i][j] %= 10;
          }
        }
      }
      ks = nks;
    left /= 2;
  }
  int ans = 0;
  for (int i=0;i<3;i++) {
    ans += mat[2][i]*fst[i];
    ans %= 10;
  }
  cout << ans << endl;
}