#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
#include<tuple>
using namespace std;
typedef long long ll;
typedef unsigned int ui;
const ll mod = 1000000007;
const ll INF = (ll)1000000007 * 1000000007;
typedef pair<int, int> P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define Per(i,sta,n) for(int i=n-1;i>=sta;i--)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
typedef long double ld;
typedef complex<ld> Point;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<ll, ll> LP;

int n;
ll a,b;

typedef vector< vector< ll > > mat;
typedef vector< ll > vec;
mat mtmul(mat &A, mat &B){
	mat C(A.size(), vec(B[0].size()));
	   rep(i, (int)A.size()) {
			   rep(k, (int)B.size()) {
					   rep(j, (int)B[0].size()) {
						   C[i][j] = (C[i][j] + (A[i][k] * B[k][j]) ) ;
						   C[i][j]%=mod;
					   }
			   }
	   }
	   return C;
}
mat mtpow(mat A, ll n) {
	   mat B(A.size(), vec(A.size()));
	   rep(i, (int)A.size()) {
			   B[i][i] = 1;
	   }
	   while (n > 0) {
			   if (n&(ll)1)B = mtmul(B, A);
			   A = mtmul(A, A);
			   n >>= 1;
	   }
	   return B;
}

void solve(){
	cin >> a >> b >> n;
	mat A={{a,b},
	       {1,0}};
	A=mtpow(A,n-1);
	
	mat a={{1},{0}};
	ll ans=mtmul(A,a)[0][0];
	cout << ans << endl;
}

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout << fixed << setprecision(50);
	solve();
}