#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>

#include <chrono>
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

const long long MAX = 510000;
const long long INF = 1LL << 61;
const long long MOD = 1000000007LL;
const long long mod = 998244353LL;


using namespace std;
typedef unsigned long long ull;
typedef  long long ll;


struct Matrix {
	vector<vector<long long> > val;
	Matrix(int n, int m, long long x = 0) : val(n, vector<long long>(m, x)) {}
	void init(int n, int m, long long x = 0) { val.assign(n, vector<long long>(m, x)); }
	size_t size() const { return val.size(); }
	inline vector<long long>& operator [] (int i) { return val[i]; }
};

Matrix operator * (Matrix A, Matrix B) {
	Matrix R(A.size(), B[0].size());
	for (int i = 0; i < A.size(); ++i)
		for (int j = 0; j < B[0].size(); ++j)
			for (int k = 0; k < B.size(); ++k)
				R[i][j] = (R[i][j] + A[i][k] * B[k][j] % MOD) % MOD;
	return R;
}

Matrix modpow(Matrix A, long long n) {
	Matrix R(A.size(), A.size());
	for (int i = 0; i < A.size(); ++i) R[i][i] = 1;
	while (n > 0) {
		if (n & 1) R = R * A;
		A = A * A;
		n >>= 1;
	}
	return R;
}

int main()
{
	ll a, b, n;
	cin >> a >> b >> n;
	Matrix m1(2, 2), m2(2, 1);
	m2[0][0] = 1;
	m1[0][0] = a;
	m1[0][1] = b;
	m1[1][0] = 1;
	Matrix res = modpow(m1, n - 1) * m2;
	cout << res[0][0] << endl;
	return 0;
}