#include <iostream>
using namespace std;
using ll = long long;
const int MOD = 1e9+7;
#define rep(i,n) for(int i=0;i<(n);++i)

struct Matrix {
  ll a, b, c, d;
public:
  Matrix(ll a, ll b, ll c, ll d) : a(a % MOD), b(b % MOD), c(c % MOD), d(d % MOD) {}
};

Matrix mul(Matrix A, Matrix B) {
  return Matrix(A.a * B.a + A.b * B.c, A.a * B.b + A.b * B.d, A.c * B.a + A.d * B.c, A.c * B.b + A.d * B.d);
}
Matrix pow(Matrix A, int p) {
  if (p == 1)
    return A;
  if (p % 2 == 0)
    return pow(mul(A, A), p / 2);
  else
    return mul(pow(mul(A, A), p / 2), A);
}

int main() {
  int a, b, n;
  cin >> a >>  b >>  n;

  if (n == 0)
    cout << 0 << endl;
  else if (n == 1)
    cout << 1 << endl;
  else {
    Matrix m(0, 1, b, a);
    m = pow(m, n-1);
    cout << m.d << endl;
  }

  return 0;
}