#include <algorithm>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <tuple>
#include <vector>

#define mkp make_pair
#define mkt make_tuple
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define all(v) v.begin(), v.end()
using namespace std;
typedef long long ll;
const ll MOD = 10;
// const ll MOD = 998244353;
template <class T>
void chmin(T &a, const T &b) {
    if (a > b) a = b;
}
template <class T>
void chmax(T &a, const T &b) {
    if (a < b) a = b;
}

typedef vector<ll> vec;
typedef vector<vec> mat;

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

// C=pow(A,n)
mat pow(mat A, ll n) {
    mat B(A.size(), vec(A.size()));
    for (int i = 0; i < A.size(); i++) {
        B[i][i] = 1;
    }
    while (n > 0) {
        if (n & 1) B = mul(B, A);
        A = mul(A, A);
        n = (n >> 1);
    }
    return B;
}

void solve() {
    int P, Q, R;
    cin >> P >> Q >> R;
    ll K;
    cin >> K;

    P %= 10;
    Q %= 10;
    R %= 10;
    K -= 3;

    mat M(3, vec(3, 0));
    M[0][0] = 1;
    M[0][1] = 1;
    M[0][2] = 1;
    M[1][0] = 1;
    M[2][1] = 1;
    M = pow(M, K);

    mat B(3, vec(1, 0));
    B[0][0] = R;
    B[1][0] = Q;
    B[2][0] = P;

    mat A = mul(M, B);

    cout << A[0][0] << endl;
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    solve();

    return 0;
}