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

using namespace std;

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

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

string yn(bool f){return f?"Yes":"No";}
string YN(bool f){return f?"YES":"NO";}

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(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	cout<<fixed<<setprecision(10);
	
	int a, b, n;
	vector<vector<int>> mat(3, vector<int>(3,0)),  ans(3, vector<int>(1,0));
	
	cin>>a>>b>>n;
	
	mat[0][0] = a;
	mat[0][1] = b;
	mat[1][0] = 1;
	mat[2][1] = 1;
	
	ans[0][0] = a;
	ans[1][0] = 1;
	ans[2][0] = 0;
	
	mat = matrix_power(mat, n);
	
	ans = product(mat, ans);
	
	
	cout<<ans[2][0]<<endl;
	
	return 0;
}