#include<iostream>
#include<string>
#include<iomanip>
#include<cmath>
#include<vector>
#include<algorithm>
#include<utility>

using namespace std;

#define int long long
#define endl "\n"

constexpr long long INF = (long long)1e18;
constexpr long long MOD = 1'000'000'007; 

struct fast_io {
	fast_io(){
		std::cin.tie(nullptr);
		std::ios::sync_with_stdio(false);
	};
} fio;


template<typename type>
vector<vector<type>> product(vector<vector<type>> &a, vector<vector<type>> &b){
	vector<vector<type>> res(a.size(),vector<type>(b[0].size(),0));
	
	
	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++){ 
				res[i][j] += a[i][k]*b[k][j];
				res[i][j] %= MOD;
			}
		}
	}
	
	return res;
}

template<typename type>
vector<vector<type>> matrix_power(vector<vector<type>> matrix, long long n){
	vector<vector<type>> res(matrix.size(), vector<type>(matrix.size(),0));
	
	for(int i = 0; i < matrix.size(); i++) res[i][i] = 1;
	
	for( ; n > 0; n >>= 1){
		if(n&1) res = product(res,matrix);
		matrix = product(matrix,matrix);
	}
	
	return res;
}

signed main(){
	cout<<fixed<<setprecision(10);
	
    int a, b;
    int n;
    int ans = 0;
    
	vector<vector<int>> matrix1(4,vector<int>(4)), matrix2(4,vector<int>(4));
	vector<vector<int>> ans1(4,vector<int>(1)), ans2(4,vector<int>(1));
	
    cin>>a>>b;
    cin>>n;
    
    ans1[0][0] = 1;
    ans2[0][0] = 1;
    
    matrix1[0][0] = a;
    matrix1[0][1] = b;
    
	matrix1[1][0] = 1;
    matrix1[1][1] = a;
    
    matrix1[2][0] = 1;
    matrix1[3][1] = 1;
    
    matrix2 = matrix1;
    
    matrix2[0][1] *= -1;
    matrix2[1][0] *= -1;
    
    matrix1 = matrix_power(matrix1,n);
	ans1 = product(matrix1,ans1);
    
    matrix2 = matrix_power(matrix2,n);
	ans2 = product(matrix2,ans2);
    
    ans = ans1[0][0] + ans2[0][0];
    ans %= MOD;
    
    cout<<ans<<endl;
    
	return 0;
}