#include "bits/stdc++.h"
#define int long long

using namespace std;
using ll = long long;
using P = pair<ll, ll>;
const ll INF = (1LL << 61);
ll mod = 10;
struct mint {
	ll x; // typedef long long ll;
	mint(ll x = 0) :x((x%mod + mod) % mod) {}
	mint operator-() const { return mint(-x); }
	mint& operator+=(const mint a) {
		if ((x += a.x) >= mod) x -= mod;
		return *this;
	}
	mint& operator-=(const mint a) {
		if ((x += mod - a.x) >= mod) x -= mod;
		return *this;
	}
	mint& operator*=(const mint a) {
		(x *= a.x) %= mod;
		return *this;
	}
	mint operator+(const mint a) const {
		mint res(*this);
		return res += a;
	}
	mint operator-(const mint a) const {
		mint res(*this);
		return res -= a;
	}
	mint operator*(const mint a) const {
		mint res(*this);
		return res *= a;
	}
	mint pow(ll t) const {
		if (!t) return 1;
		mint a = pow(t >> 1);
		a *= a;
		if (t & 1) a *= *this;
		return a;
	}

	// for prime mod
	mint inv() const {
		return pow(mod - 2);
	}
	mint& operator/=(const mint a) {
		return (*this) *= a.inv();
	}
	mint operator/(const mint a) const {
		mint res(*this);
		return res /= a;
	}
};
istream& operator>>(istream& is, mint& a) { return is >> a.x; }
ostream& operator<<(ostream& os, const mint& a) { return os << a.x; }
template< class T >
struct Matrix {
	vector< vector< T > > A;

	Matrix() {}

	Matrix(size_t n, size_t m) : A(n, vector< T >(m, 0)) {}

	Matrix(size_t n) : A(n, vector< T >(n, 0)) {};

	size_t height() const {
		return (A.size());
	}

	size_t width() const {
		return (A[0].size());
	}

	inline const vector< T > &operator[](int k) const {
		return (A.at(k));
	}

	inline vector< T > &operator[](int k) {
		return (A.at(k));
	}

	static Matrix I(size_t n) {
		Matrix mat(n);
		for (int i = 0; i < n; i++) mat[i][i] = 1;
		return (mat);
	}

	Matrix &operator+=(const Matrix &B) {
		size_t n = height(), m = width();
		assert(n == B.height() && m == B.width());
		for (int i = 0; i < n; i++)
			for (int j = 0; j < m; j++)
				(*this)[i][j] += B[i][j];
		return (*this);
	}

	Matrix &operator-=(const Matrix &B) {
		size_t n = height(), m = width();
		assert(n == B.height() && m == B.width());
		for (int i = 0; i < n; i++)
			for (int j = 0; j < m; j++)
				(*this)[i][j] -= B[i][j];
		return (*this);
	}

	Matrix &operator*=(const Matrix &B) {
		size_t n = height(), m = B.width(), p = width();
		assert(p == B.height());
		vector< vector< T > > C(n, vector< T >(m, 0));
		for (int i = 0; i < n; i++)
			for (int j = 0; j < m; j++)
				for (int k = 0; k < p; k++)
					C[i][j] = (C[i][j] + (*this)[i][k] * B[k][j]);
		A.swap(C);
		return (*this);
	}

	Matrix &operator^=(long long k) {
		Matrix B = Matrix::I(height());
		while (k > 0) {
			if (k & 1) B *= *this;
			*this *= *this;
			k >>= 1LL;
		}
		A.swap(B.A);
		return (*this);
	}

	Matrix operator+(const Matrix &B) const {
		return (Matrix(*this) += B);
	}

	Matrix operator-(const Matrix &B) const {
		return (Matrix(*this) -= B);
	}

	Matrix operator*(const Matrix &B) const {
		return (Matrix(*this) *= B);
	}

	Matrix operator^(const long long k) const {
		return (Matrix(*this) ^= k);
	}

	friend ostream &operator<<(ostream &os, Matrix &p) {
		size_t n = p.height(), m = p.width();
		for (int i = 0; i < n; i++) {
			os << "[";
			for (int j = 0; j < m; j++) {
				os << p[i][j] << (j + 1 == m ? "]\n" : ",");
			}
		}
		return (os);
	}


	T determinant() {
		Matrix B(*this);
		assert(width() == height());
		T ret = 1;
		for (int i = 0; i < width(); i++) {
			int idx = -1;
			for (int j = i; j < width(); j++) {
				if (B[j][i] != 0) idx = j;
			}
			if (idx == -1) return (0);
			if (i != idx) {
				ret *= -1;
				swap(B[i], B[idx]);
			}
			ret *= B[i][i];
			T vv = B[i][i];
			for (int j = 0; j < width(); j++) {
				B[i][j] /= vv;
			}
			for (int j = i + 1; j < width(); j++) {
				T a = B[j][i];
				for (int k = 0; k < width(); k++) {
					B[j][k] -= B[i][k] * a;
				}
			}
		}
		return (ret);
	}
};
signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	int p, q, r, K; cin >> p >> q >> r >> K;
	Matrix<mint> A(3, 3), B(3, 1);
	A[0][0] = 1;
	A[0][1] = 1;
	A[0][2] = 1;
	A[1][0] = 1;
	A[2][1] = 1;
	B[0][0] = r;
	B[1][0] = q;
	B[2][0] = p;
	A ^= K - 1;
	A *= B;
	cout << A[2][0] << endl;
	return 0;


}