#include <iostream>
#include <vector>
#include <limits.h>
#include <algorithm>
#include <string>
#include <math.h>
#include <limits.h>
#include <queue>
#include <map>
#include <set>
#include <iomanip>
#include <bitset>
#include <cassert>
#include <random>
#include <functional>
#include <stack>
#include <iomanip>
#include <cassert>
//#include <boost/multiprecision/cpp_int.hpp>
#include <complex>
#include <cstdio>
#include <list>

//< in.txt > out.txt
using namespace std;
//std::ios::sync_with_stdio(false);
//std::cin.tie(0);
const long long MOD = 1e9 + 7;
typedef long long LL;
typedef long double LD;
typedef pair<LL, LL> PLL;
typedef pair<LD, LL> PDL;
typedef pair<LD, LD> PDD;
typedef vector<LL> VLL;
typedef vector<VLL> VVLL;
//typedef boost::multiprecision::cpp_int bigint;

template<class T>
void in(T& x) {
	cin >> x;
}

template<class T1, class T2>
void in(pair<T1, T2>& p) {
	in(p.first);
	in(p.second);
}

template<class T>
void in(vector<T>& v, LL st = -1, LL en = -1) {
	if (st == -1) {
		st = 0;
		en = v.size() - 1;
	}
	for (LL n = st; n <= en; n++) {
		in(v[n]);
	}
}

VVLL modpow(VVLL base, LL p) {
	if (p == 0) {
		VVLL res;
		res.resize(2, VLL(2, 0));
		res[0][0] = 1;
		res[1][1] = 1;
		return res;
	}
	if (p == 1) return base;
	VVLL res = modpow(base, p / 2);
	VVLL temp;
	temp.resize(2, VLL(2,0));
	for (LL x = 0; x < 2; x++) {
		for (LL y = 0; y < 2; y++) {
			for (LL k = 0; k < 2; k++) {
				temp[x][y] += res[x][k] * res[k][y];
				temp[x][y] %= MOD;
			}
		}
	}
	if (p % 2 == 0)return temp;
	VVLL temp2;
	temp2.resize(2, VLL(2, 0));
	for (LL x = 0; x < 2; x++) {
		for (LL y = 0; y < 2; y++) {
			for (LL k = 0; k < 2; k++) {
				temp2[x][y] += temp[x][k] * base[k][y];
				temp2[x][y] %= MOD;
			}
		}
	}
	return temp2;
}

int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(0);
	LL a, b, n;
	cin >> a >> b >> n;
	if (n == 0) {
		cout << 0 << "\n";
		return 0;
	}
	else if (n == 1) {
		cout << 1 << "\n";
		return 0;
	}
	VVLL base;
	base.resize(2, VLL(2, 0));
	base[0][0] = a;
	base[0][1] = b;
	base[1][0] = 1;
	base = modpow(base, n - 1);
	cout << (base[0][0] + MOD) % MOD << "\n";
	return 0;
}