#include "iostream"
#include "climits"
#include "list"
#include "queue"
#include "stack"
#include "set"
#include "functional"
#include "algorithm"
#include "string"
#include "map"
#include "unordered_map"
#include "unordered_set"
#include "iomanip"
#include "cmath"
#include "random"
#include "bitset"
#include "cstdio"
#include "numeric"
#include "cassert"
#include "ctime"

using namespace std;

constexpr long long int MOD = 1000000007;
//constexpr int MOD = 1000000007;
//constexpr int MOD = 998244353;
//constexpr long long int MOD = 998244353;
constexpr double EPS = 1e-8;

//int N, M, K, T, H, W, L, R;
long long int N, M, K, T, H, W, L, R;

vector<vector<long long int>>matrix_product(vector<vector<long long int>>v, vector<vector<long long int>>w) {
	vector<vector<long long int>>ret(v.size(), vector<long long int>(w.front().size()));
	for (int i = 0; i < ret.size(); i++) {
		for (int j = 0; j < ret[i].size(); j++) {
			for (int k = 0; k < w.size(); k++) {
				ret[i][j] += v[i][k] * w[k][j];
				ret[i][j] %= 10;
			}
		}
	}
	return ret;
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	cin >> N >> M >> K >> L;
	N %= 10, M %= 10, K %= 10;
	vector<vector<long long>>by(3, vector<long long>(3));
	by[0][0] = by[0][1] = by[0][2] = by[1][0] = by[2][1] = 1;
	L -= 3;
	vector<vector<long long>>box(3, vector<long long>(1));
	box[2][0] = N;
	box[1][0] = M;
	box[0][0] = K;
	for (int i = 0; i < 60; i++) {
		if (L >> i & 1) {
			box = matrix_product(by, box);
		}
		by = matrix_product(by, by);
	}
	cout << box[0][0] << endl;
}