#pragma GCC optimize("O3")
#include <algorithm>

#include <bits/stdc++.h>
#define ll long long
#define rep(i,n) for(ll i=0;i<(n);i++)
#define pll pair<ll,ll>
#define pii pair<int,int>
#define pq priority_queue
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define endl '\n'
#define ios ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define lb(c,x) distance(c.begin(),lower_bound(all(c),x))
#define ub(c,x) distance(c.begin(),upper_bound(all(c),x))

using namespace std;



template<class T> inline bool chmax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T> inline bool chmin(T& a,T b){if(a>b){a=b;return 1;}return 0;}

const int INF=1e9;

using vv=vector<vector<ll>>;
const ll MOD=1e9+7;

vv E(int n) //行列の初期化（単位行列）
{
  vv res(n, vector<ll>(n));
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++)
      res[i][j] = (i == j); //対角成分を1に、それ以外を0にする。
  return res;
}

vv matprod(vv A, vv B) //行列の掛け算
{
  int l = A.size(), m = B.size(), n = B[0].size();
  vv res(l, vector<ll>(n, 0));
  for (int i = 0; i < l; i++)
    for (int j = 0; j < n; j++)
      for (int k = 0; k < m; k++)
        res[i][j] = (res[i][j] + A[i][k] * B[k][j]) % MOD;
  return res;
}

vv matpow(vv A, ll n) //行列累乗
{
  vv p = A, res = E(A.size());
  while (n > 0)
  {
    if (n & 1)
      res = matprod(res, p);
    p = matprod(p, p);
    n >>= 1;
  }
  return res;
}




int main(){
    ll a,b,n;
    cin >> a >> b >> n;
    if(n==0){
        cout << 2 << endl;
        return 0;
    }
    n-=1;
    vv c(2,vector<ll>(1));
    c[0][0]=2*a;
    c[0][0]%=MOD;
    c[1][0]=2;
    vv tran(2,vector<ll>(2));
    tran[0][0]=2*a;
    tran[0][0]%=MOD;
    tran[0][1]=b-a*a;
    if(b-a*a<0){
        ll s=abs(b-a*a);
        ll num=s/MOD+1;
        tran[0][1]+=num*MOD;
    }
    tran[0][1]%=MOD;
    tran[1][0]=1;
    tran[1][1]=0;
    tran=matpow(tran,n);
    c=matprod(tran,c);
    cout << c[0][0] << endl;
    return 0;
}