#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (n);i++)
#define sz(x) int(x.size())
typedef unsigned long long ll;
typedef long double ld;
typedef pair<int,int> P;
constexpr int mod = 1e9+7;
struct mint {
  ll x; // typedef long long ll;
  mint(ll x=0):x((x%mod+mod)%mod){}
  mint operator-() const { return mint(-x);}
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += mod-a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this;}
  mint operator+(const mint a) const { return mint(*this) += a;}
  mint operator-(const mint a) const { return mint(*this) -= a;}
  mint operator*(const mint a) const { return mint(*this) *= a;}
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t>>1);
    a *= a;
    if (t&1) a *= *this;
    return a;
  }
 
  // for prime mod
  mint inv() const { return pow(mod-2);}
  mint& operator/=(const mint a) { return *this *= a.inv();}
  mint operator/(const mint a) const { return mint(*this) /= a;}
};

typedef vector<mint> vec;
typedef vector<vec> mat;

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

  if (n == 0) {
    cout << 0 << endl;
    return 0;
  }
  if (n == 1) {
    cout << 1 << endl;
    return 0;
  }
 
  vec dp(3, 0);
  mat A(3, vec(3, 0));
  A[0][0] = a, A[0][1] = b;
  A[1][0] = A[2][1] = 1;
  dp[0] = a, dp[1] = 1;
  n -= 2;

  auto update = [&](){
    vec ndp(3, 0);
    for (int i = 0; i < 3; i++) {
      for (int j = 0; j < 3; j++) ndp[i] += A[i][j] * dp[j];
    }
    dp = move(ndp);
  };

  auto pow_mat = [&](){
    mat B(3, vec(3, 0));
    for (int i = 0; i < 3; i++) {
      for (int j = 0; j < 3; j++) {
        for (int k = 0; k < 3; k++) B[i][j] += A[i][k] * A[k][j];
      }
    }
    A = move(B);
  };

  while (n) {
    if (n & 1) update();
    pow_mat();
    n >>= 1;
  }
  cout << dp[0].x << endl;
  return 0;
}