#include <iostream>
#include <algorithm>
#include <string>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <vector>
#include <list>
#include <deque>
#include <set>
#include <map>
#include <queue>
#include <bitset>

using namespace std;

long long mod = 1000000007;
int main() {
	long long a, b, n; cin >> a >> b >> n;

	if (n <= 1) {
		cout << n << endl;
		return 0;
	}

	long long x1 = 1, x2 = 0, x3 = 0, x4 = 1;
	long long y1, y2, y3, y4;
	long long a1 = a, a2 = b, a3 = 1, a4 = 0;
	while (n > 0) {
		if (n % 2 == 1) {
			y1 = (a1 * x1 + a2 * x3) % mod; y2 = (a1 * x2 + a2 * x4) % mod;
			y3 = (a3 * x1 + a4 * x3) % mod; y4 = (a3 * x2 + a4 * x4) % mod;
			x1 = y1; x2 = y2; x3 = y3; x4 = y4;
		}
		{
			y1 = (a1 * a1 + a2 * a3) % mod; y2 = (a1 * a2 + a2 * a4) % mod;
			y3 = (a3 * a1 + a4 * a3) % mod; y4 = (a3 * a2 + a4 * a4) % mod;
			a1 = y1; a2 = y2; a3 = y3; a4 = y4;
		}
		n /= 2;
	}

	cout << x3 << endl;

	return 0;
}