#include <iostream>
#include <vector>

using namespace std;
typedef long long ll;
typedef vector<vector<ll>> vvl;
ll n,mod = 1000000007;
vvl mul(const vvl &a,const vvl &b){
	vvl c(n,vector<ll>(n,0));
	int i,j,k;
	for(i=0;i<n;i++){
		for(j=0;j<n;j++){
			ll x = 0;
			for(k=0;k<n;k++){
				(x += a[i][k]*b[k][j]) %= mod;
			}
			c[i][j] = x;
		}
	}
	return c;
}

vvl pw(const vvl &a, ll x){
	vvl ret(n,vector<ll>(n,0)),b(n,vector<ll>(n,0));
	int i,j,k;
	for(i=0;i<n;i++){
		ret[i][i] = 1;
	}
	for(i=0;i<n;i++){
		for(j=0;j<n;j++){
			b[i][j] = a[i][j];
		}
	}
	while(x){
		while(!(x&1)){
			b = mul(b,b);
			x /= 2;
		}
		ret = mul(ret,b);
		x--;
	}
	return ret;
}

vector<ll> mul2(const vvl &a, const vector<ll> &b){
	vector<ll> c(n,0);
	int i,j;
	for(i=0;i<n;i++){
		ll x = 0;
		for(j=0;j<n;j++){
			(x += a[i][j]*b[j]) %= mod;
		}
		c[i] = x;
	}
	return c;
}

int main(){
	long long a,b,x;
	cin >> a >> b >> x;
	n = 2;
	vector<ll> v(2,0);
	v[0] = 1;
	vvl m(2,vector<ll>(2,0));
	m[0][0] = a; m[0][1] = b; m[1][0] = 1;
	m = pw(m,x);
	cout << mul2(m,v)[1] << endl;
}