//#include <atcoder/all>
#include <iostream>
#include <numeric>
#include <cmath>
#include <limits>
#include <stdio.h>
#include <iomanip>
#include <string> // string, to_string, stoi
#include <vector> // vector
#include <algorithm> // min, max, swap, sort, reverse, lower_bound, upper_bound
#include <utility> // pair, make_pair
#include <tuple> // tuple, make_tuple
#include <cstdint> // int64_t, int*_t
#include <cstdio> // printf
#include <map> // map
#include <queue> // queue, priority_queue
#include <set> // set
#include <stack> // stack
#include <deque> // deque
#include <unordered_map> // unordered_map
#include <unordered_set> // unordered_set
#include <bitset> // bitset
#include <cctype> // isupper, islower, isdigit, toupper, tolower
using namespace std;
//using namespace atcoder;
using ll = long long;
#define all(A) A.begin(),A.end()
using vll = vector<ll>;
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)
using Graph = vector<vector<int>>;

vector<ll> ISP;
ll M = 1500005;
void PP(ll M) {
	ISP.assign(M + 1, -1);
	for (ll i = 2; i <= M; i++) {
		ISP[i] = i;
	}

	ISP[0] = -1;
	ISP[1] = -1;
	for (ll i = 2; i * i <= M; i++) {
		if (ISP[i] == i) {

			for (ll j = 2; i * j <= M; j++) {
				if (ISP[i * j] != i * j)continue;

				ISP[i * j] = i;
			}
		}
	}


}

vector<ll> power(70);
ll mod = 1000000007;
vector<vector<vector<ll>>> matrixpow;
void prematrixpow(vector<vll> matrix) {
	ll N = matrix.size();
	matrixpow.assign(70, vector<vll>(N, vll(N)));
	rep(h, N) {
		rep(w, N) {
			matrixpow[0][h][w] = matrix[h][w];
		}
	}
	rep(k, 69) {
		rep(h, N) {
			rep(w, N) {
				ll S = 0;
				rep(i, N) {
					S += matrixpow[k][h][i] * matrixpow[k][i][w];
					S %= mod;
					S = (S + mod) % mod;
				}
				matrixpow[k + 1][h][w] = S;
			}
		}
	}

}
vector<vll> modmatrixpow(ll K) {
	ll P = K;
	ll N = matrixpow[0].size();
	vector<vll> res(N, vll(N, 0));
	rep(i, N) {
		res[i][i] = 1;
	}

	rep(j, 70) {
		if (P % 2 != 0) {
			vector<vll> res2(N, vll(N, 0));

			rep(h, N) {
				rep(w, N) {
					ll S = 0;
					rep(i, N) {
						S += matrixpow[j][h][i] * res[i][w];
						S %= mod;
						S = (S + mod) % mod;
					}
					res2[h][w] = S;
				}
			}
			res = res2;
		}
		P /= 2;
	}

	return res;


}


int main() {
	ll A, B, N;
	cin >> A >> B >> N;
	vector<vll> M = { {A,B},{1,0}};
	prematrixpow(M);
	if (N == 0) {
		cout << 0 << endl;

		return 0;
	}
	vector<vll> Aa = modmatrixpow(N-1);
	cout << Aa[0][0] << endl;
}