/* -*- coding: utf-8 -*-
 *
 * 1595.cc:  No.1595 The Final Digit - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int N = 3;

/* typedef */

typedef long long ll;
typedef int vec[N];
typedef vec mat[N];

/* global variables */

mat ma, mb;
vec va, vb;

/* subroutines */

inline void initvec(vec a) { memset(a, 0, sizeof(vec)); }
inline void initmat(mat a) { memset(a, 0, sizeof(mat)); }

inline void unitmat(mat a) {
  initmat(a);
  for (int i = 0; i < N; i++) a[i][i] = 1;
}

inline void copymat(const mat a, mat b) {
  memcpy(b, a, sizeof(mat));
}

inline void mulmat(const mat a, const mat b, mat c) {
  for (int i = 0; i < N; i++)
    for (int j = 0; j < N; j++) {
      c[i][j] = 0;
      for (int k = 0; k < N; k++)
        c[i][j] = (c[i][j] + a[i][k] * b[k][j]) % 10;
    }
}

inline void powmat(const mat a, ll b, mat c) {
  mat s, t;
  copymat(a, s);
  unitmat(c);

  while (b > 0) {
    if (b & 1) {
      mulmat(c, s, t);
      copymat(t, c);
    }

    mulmat(s, s, t);
    copymat(t, s);
    b >>= 1;
  }
}

inline void mulmatvec(const mat a, const vec b, vec c) {
  for (int i = 0; i < N; i++) {
    c[i] = 0;
    for (int j = 0; j < N; j++) c[i] = (c[i] + a[i][j] * b[j]) % 10;
  }
}

/* main */

int main() {
  int p, q, r;
  ll k;
  scanf("%d%d%d%lld", &p, &q, &r, &k);

  ma[0][0] = 1, ma[0][1] = 1, ma[0][2] = 1;
  ma[1][0] = 1, ma[1][1] = 0, ma[1][2] = 0;
  ma[2][0] = 0, ma[2][1] = 1, ma[2][2] = 0;
  powmat(ma, k - 3, mb);

  va[0] = r % 10, va[1] = q % 10, va[2] = p % 10;
  mulmatvec(mb, va, vb);

  printf("%d\n", vb[0]);
  return 0;
}