#include <bits/stdc++.h>

using namespace std;

const long long MOD = 1e9 + 7;

typedef vector<long long> vec;
typedef vector<vec> matrix;

matrix eye(int n) {
  matrix mat(n, vec(n));
  for (int i = 0; i < n; i++) {
    mat[i][i] = 1;
  }
  return mat;
}

matrix zeros(int r, int c) {
  return matrix(r, vec(c));
}

matrix zeros(int n) {
  return zeros(n, n);
}

matrix add(const matrix &a, const matrix &b) {
  matrix c = zeros(a.size(), a[0].size());
  for (int i = 0; i < c.size(); i++) {
    for (int j = 0; j < c[0].size(); j++) {
      c[i][j] = a[i][j] + b[i][j];
    }
  }
  return c;
}

matrix mul(const matrix &a, const matrix &b) {
  matrix c = zeros(a.size(), b[0].size());
  for (int i = 0; i < a.size(); i++) {
    for (int k = 0; k < b.size(); k++) {
      for (int j = 0; j < b[0].size(); j++) {
        c[i][j] += a[i][k] * b[k][j];
      }
    }
  }
  return c;
}

matrix modmul(const matrix &a, const matrix &b, long long mod) {
  matrix c = zeros(a.size(), b[0].size());
  for (int i = 0; i < a.size(); i++) {
    for (int k = 0; k < b.size(); k++) {
      for (int j = 0; j < b[0].size(); j++) {
        c[i][j] = (c[i][j] + a[i][k] * b[k][j]) % mod;
      }
    }
  }
  return c;
}

matrix pow(const matrix &a, long long p) {
  matrix ret = eye(a.size());
  matrix x = a;
  while (p) {
    if (p & 1)
      ret = mul(ret, x);
    x = mul(x, x);
    p >>= 1;
  }
  return ret;
}

matrix modpow(const matrix &a, long long p, long long mod) {
  matrix ret = eye(a.size());
  matrix x = a;
  while (p) {
    if (p & 1)
      ret = modmul(ret, x, mod);
    x = modmul(x, x, mod);
    p >>= 1;
  }
  return ret;
}

long long solve(long long a, long long b, long long n) {
  if (n == 0) return 2;
  if (n == 1) return 2 * a % MOD;

  matrix A = eye(2);
  A[0][0] = 2 * a % MOD;  A[0][1] = ((b - a * a) % MOD + MOD) % MOD;
  A[1][0] = 1;            A[1][1] = 0;
  
  A = modpow(A, n-1, MOD);
  return (2 * a * A[0][0] % MOD + 2 * A[0][1] % MOD) % MOD;
}

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  long long a, b, n;
  cin >> a >> b >> n;

  cout << solve(a, b, n) << endl;
  
  return 0;
}