#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;

vector<vector<long long>> mul(const vector<vector<long long>>& a, const vector<vector<long long>>& b) {
  int n = (int) a.size();
  vector<vector<long long>> res(n, vector<long long>(n));
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < n; ++j) {
      for (int k = 0; k < n; ++k) {
        (res[i][j] += a[i][k] * b[k][j] % mod) %= mod;
      }
    }
  }
  return res;
}

vector<vector<long long>> power(vector<vector<long long>> a, long long k) {
  int n = (int) a.size();
  vector<vector<long long>> res(n, vector<long long>(n));
  for (int i = 0; i < n; i++) res[i][i] = 1;
  while (k) {
    if (k & 1) res = mul(res, a);
    a = mul(a, a);
    k >>= 1;
  }
  return res;
}

signed main() {
  ios::sync_with_stdio(false); cin.tie(0);
  long long a, b, n;
  cin >> a >> b >> n;
  vector<vector<long long>> x = {{a, b}, {1, 0}};
  vector<vector<long long>> y = {{1}, {0}};
  vector<vector<long long>> z = power(x, n);
  vector<vector<long long>> res = mul(z, y);
  cout << res[1][0] << '\n';
  return 0;
}