#include <iostream>
#include <cstdio>
#include <string>
#include <algorithm>
#include <utility>
#include <cmath>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <tuple>
#include <numeric>
#include <functional>
using namespace std;
typedef long long ll;
typedef vector<ll> vl;
typedef vector<vector<ll>> vvl;
typedef pair<ll, ll> P;
#define rep(i, n) for(ll i = 0; i < n; i++)
#define exrep(i, a, b) for(ll i = a; i <= b; i++)
#define out(x) cout << x << endl
#define exout(x) printf("%.10f\n", x)
#define chmax(x, y) x = max(x, y)
#define chmin(x, y) x = min(x, y)
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define pb push_back
#define re0 return 0
const ll mod = 10;
const ll INF = 1e16;

/* 
    線形k項間漸化式

    a_k = Σ d_i * a_i (0 <= i < k)
    
    の第n項の値のmodを O(k^2 * log(n)) で求める。(きたまさ法)

    ll k;  // k項間漸化式
    ll n;  // 第n項(nは0-index)の値を求める
    vl a;  // 初期値ベクトル (a_0,a_1,…,a_(k-1)の値)
    vl d;  // 係数ベクトル
*/

vl dfs(ll k, ll m, vl &a, vl &d) {  // a_m = Σ x_i * a_i (0 <= i < k) を満たす ベクトル (x_0,x_1,…,x_(k-1)) を求める
    if(m == k) { 
        return d;
    }
    if(m%2 == 1 || m < 2*k) {
        vvl f(2, vl(k));
        f[0] = dfs(k, m-1, a, d);
        // f[0] から f[1] を求める
        f[1][0] = d[0] * f[0][k-1] % mod;
        exrep(i, 1, k-1) {
            f[1][i] = (f[0][i-1] + d[i] * f[0][k-1]) % mod;
        }
        return f[1];
    }
    else {
        vvl f(k, vl(k));
        f[0] = dfs(k, m/2, a, d);
        // f[0] から f[1],f[2],…,f[k-1] を求める
        exrep(i, 1, k-1) {
            f[i][0] = d[0] * f[i-1][k-1] % mod;
            exrep(j, 1, k-1) {
                f[i][j] = (f[i-1][j-1] + d[j] * f[i-1][k-1]) % mod;
            }
        }
        vl f_2m(k);
        // f[0],f[1],…,f[k-1] から f[2m] を求める 
        rep(j, k) {
            rep(i, k) {
                f_2m[i] = (f_2m[i] + f[0][j] * f[j][i] % mod) % mod;
            }
        }
        return f_2m;
    }
}
 
ll kitamasa(ll k, ll n, vl &a, vl &d) {
    if(n < k) {
        return a[n];
    } 
    vl x = dfs(k, n, a, d);
    ll res = 0;
    rep(i, k) {
        res = (res + x[i] * a[i] % mod) % mod;
    }
    return res;
}
 
int main() {

    ll k = 3;

    vl a(3);
    rep(i, 3) {
        cin >> a[i];
    }

    ll n;
    cin >> n;
    n--;

    vl d(3, 1);
    
    out(kitamasa(k, n, a, d));
    re0;
}