#include <bits/stdc++.h>

#define For(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
#define rFor(i, a, b) for (int i = (int)(a)-1; i >= (int)(b); --i)
#define rep(i, n) For(i, 0, (n))
#define rrep(i, n) rFor(i, (n), 0)
#define fi first
#define se second

using namespace std;

typedef long long lint;
typedef unsigned long long ulint;
typedef pair<int, int> pii;
typedef pair<lint, lint> pll;

template <class T>
bool chmax(T &a, const T &b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
template <class T>
bool chmin(T &a, const T &b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

template <class T>
T div_floor(T a, T b) {
    if (b < 0) a *= -1, b *= -1;
    return a >= 0 ? a / b : (a + 1) / b - 1;
}
template <class T>
T div_ceil(T a, T b) {
    if (b < 0) a *= -1, b *= -1;
    return a > 0 ? (a - 1) / b + 1 : a / b;
}

template <typename T>
struct coord_comp {
    vector<T> v;
    bool sorted = false;

    coord_comp() {}

    int size() { return v.size(); }

    void add(T x) { v.push_back(x); }

    void build() {
        sort(v.begin(), v.end());

        v.erase(unique(v.begin(), v.end()), v.end());
        sorted = true;
    }

    int get_idx(T x) {
        assert(sorted);
        return lower_bound(v.begin(), v.end(), x) - v.begin();
    }

    T &operator[](int i) { return v[i]; }
};

constexpr lint mod = 1000000007;
constexpr lint INF = mod * mod;
constexpr int MAX = 200010;

tuple<int, int, int> table[10][10][10][60];

int main() {
    rep(i, 10) rep(j, 10) rep(k, 10)
        table[i][j][k][0] = {j, k, (i + j + k) % 10};
    For(l, 1, 60) rep(i, 10) rep(j, 10) rep(k, 10) {
        auto [a, b, c] = table[i][j][k][l - 1];
        table[i][j][k][l] = table[a][b][c][l - 1];
    }

    int p, q, r;
    lint K;
    scanf("%d%d%d%lld", &p, &q, &r, &K);
    p %= 10;
    q %= 10;
    r %= 10;
    K -= 3;
    rep(k, 60) if (K >> k & 1) {
        auto [a, b, c] = table[p][q][r][k];
        p = a;
        q = b;
        r = c;
    }
    printf("%d\n", r);
}