#include "bits/stdc++.h"

using namespace std;
using ll = long long;

const ll MOD = 10LL;

vector<vector<ll>> prod(const vector<vector<ll>>& X, const vector<vector<ll>>& Y) {
    vector<vector<ll>> ret(3, vector<ll>(3, 0));
    for (ll i = 0; i < 3; ++i) {
        for (ll j = 0; j < 3; ++j) {
            for (ll k = 0; k < 3; ++k) {
                ret[i][j] += (X[i][k] * Y[k][j]);
                ret[i][j] %= MOD;
            }
        }
    }
    return ret;
}

vector<vector<ll>> pow(const vector<vector<ll>>& m, ll n) {
    if (n == 0) {
        vector<vector<ll>> I(3, vector<ll>(3, 0));
        I[0][0] = 1;
        I[1][1] = 1;
        I[2][2] = 1;
        return I;
    }
    if (n == 1) {
        return m;
    }
    vector<vector<ll>> half = pow(m, n / 2LL);
    vector<vector<ll>> ret = prod(half, half);
    if (n % 2LL > 0) {
        ret = prod(ret, m);
    }
    return ret;
}

void Main() {
    ll p, q, r, K;
    cin >> p >> q >> r >> K;
    p %= MOD;
    q %= MOD;
    r %= MOD;
    vector<vector<ll>> F(3, vector<ll>(3, 0));
    F[0][0] = 1;
    F[0][1] = 1;
    F[0][2] = 1;

    F[1][0] = 1;
    F[1][1] = 0;
    F[1][2] = 0;

    F[2][0] = 0;
    F[2][1] = 1;
    F[2][2] = 0;
    vector<vector<ll>> powered = pow(F, K - 3);
    ll ans = (powered[0][0] * r) % MOD;
    ans %= MOD;
    ans += (powered[0][1] * q) % MOD;
    ans %= MOD;
    ans += (powered[0][2] * p) % MOD;
    ans %= MOD;
    cout << ans << endl;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    std::cout << std::fixed << std::setprecision(15);
    Main();
    return 0;
}