#include <bits/stdc++.h>
using namespace std;
#define modulo 1000000007
#define mod(mod_x) ((((long long)mod_x+modulo))%modulo)
#define Inf 100000000


int beki(int a,int b){
	int x = 1;
	while(b!=0){
		if(b&1){
			x=mod(x*a);
		}
		a=mod(a*a);
		b>>=1;
	}
	return x;
}

struct matrix{
	vector<vector<long long>> value;
	
	matrix(int height,int width){
		value.resize(height,vector<long long>(width,0));
		if(height==width){
			for(int i=0;i<get_width();i++){
				value[i][i] = 1;
			}
		}
	}
	
	void resize(int height,int width){
		value.resize(height,vector<long long>(width,0));
		for(int i=0;i<get_width();i++){
			value[i][i] = 1;
		}
	}
	
	void set_value(vector<vector<long long>> &V){
		value = V;
	}
	
	void set_value(initializer_list<long long> list){
		auto it = list.begin();
		for(int i=0;i<get_height();i++){
			for(int j=0;j<get_width();j++){
				value[i][j]=*it;
				if(i!=get_height()-1||j!=get_width()-1)it++;
			}
		}
	}
	
	int get_width(){
		return value[0].size();
	}
	
	int get_height(){
		return value.size();
	}
	
	void print(){
		for(int i=0;i<get_height();i++){
			for(int j=0;j<get_width();j++){
				if(j!=0)cout<<' ';
				cout<<value[i][j];
			}
			cout<<endl;
		}
	}
	
};

matrix matrix_multiple(matrix &A,matrix &B){

	matrix R(A.get_height(),B.get_width());
	int multi_cnt;
	if(A.get_width()!=B.get_height()){
		assert(false);
	}
	else multi_cnt = A.get_width();
	
	for(int i=0;i<R.get_height();i++){
		for(int j=0;j<R.get_width();j++){
			R.value[i][j]=0;
			for(int k=0;k<multi_cnt;k++){
				
				R.value[i][j] = mod(R.value[i][j] + mod(A.value[i][k] * B.value[k][j]));
	
			}
		}
	}
	return R;
	
}

matrix matrix_beki(matrix A,long long cnt){
	if(A.get_width()!=A.get_height())assert(0);
	matrix R(A.get_width(),A.get_width());
	while(cnt!=0){
		if(cnt&1){
			R=matrix_multiple(R,A);
		}
		A=matrix_multiple(A,A);
		cnt>>=1;
	}
	return R;
}

int main(){
	
	int a,b,n;
	cin>>a>>b>>n;
	
	if(n==0){
		cout<<0<<endl;
	}
	else{
		matrix R(2,2);
		R.set_value({a,b,1,0});
		R = matrix_beki(R,n-1);
		cout<<R.value[0][0]<<endl;
	}
	
	return 0;
}