#include <iostream>
#include <vector>
using namespace std;
#define MOD 1000000007
//B
template <int mod>
struct ModInt{
  int n;
  ModInt():n(0){}
  ModInt(int n_):n(n_ >= 0 ? n_%mod : mod - ((-n_)%mod) ){}

  ModInt &operator+=(const ModInt &p){
    if((n+=p.n) >= mod)n-=mod;
    return *this;
  }
  ModInt &operator-=(const ModInt &p){
    n+=mod-p.n;
    if(n >= mod)n-=mod;
    return *this;
  }
  ModInt &operator*=(const ModInt &p){
    n = (int) ((1LL*n*p.n)%mod);
    return *this;
  }
  ModInt &operator/=(const ModInt &p){
    *this *= p.inverse();
    return *this;
  }
  ModInt operator-() const {return ModInt(-n);}
  ModInt operator+(const ModInt &p) const {return ModInt(*this) += p;}
  ModInt operator-(const ModInt &p) const {return ModInt(*this) -= p;}
  ModInt operator*(const ModInt &p) const {return ModInt(*this) *= p;}
  ModInt operator/(const ModInt &p) const {return ModInt(*this) /= p;}

  bool operator==(const ModInt &p) const {return n==p.n;}
	bool operator<(const ModInt &p) const {return n<p.n;}
	bool operator>(const ModInt &p) const {return n>p.n;}
	bool operator>=(const ModInt &p) const {return n>=p.n;}
	bool operator<=(const ModInt &p) const {return n<=p.n;}
  bool operator!=(const ModInt &p) const {return n!=p.n;}

  ModInt inverse() const {
    int a = n,b = mod,u = 1,v = 0;
    while(b){
      int t = a/b;
      a -= t*b; swap(a,b);
      u -= t*v; swap(u,v);
    }
    return ModInt(u);
  }

  ModInt pow(int64_t z) const {
    ModInt ret(1),mul(n);
    while(z > 0){
      if(z & 1) ret *= mul;
      mul *= mul;
      z >>= 1;
    }
    return ret;
  }

  friend ostream &operator<<(ostream &os, const ModInt &p){
    return os << p.n;
  }
  friend istream &operator>>(istream &is, ModInt &a){
    int64_t t;
    is >> t;
    a = ModInt<mod> (t);
    return (is);

  }
};
using mint = ModInt<MOD>;


template <typename T>
struct mat{
  vector<vector<T>> x;
  int h,w;
  mat():x(vector<vector<T>>()){}
  mat(int h,int w):x(vector<vector<T>>(h,vector<T>(w))),h(h),w(w){}
  mat(int h,int w, T c):x(vector<vector<T>>(h,vector<T>(w,c))),h(h),w(w){}
  vector<T> operator[](const int i)const{return x[i];}
  vector<T>& operator[](const int i){return x[i];}
  

  mat& operator*=(const mat& y){
    mat<T> ret(h,y.w,0);
    if(w != y.h){
      for(int i = 0; h > i; i++){
        for(int j = 0; y.w > j; j++){
          ret[i][j] = -1;
        }
      }
    }else{
      for(int i = 0; h > i; i++){
        for(int j = 0; y.w > j; j++){
          for(int k = 0; w > k; k++){
            ret[i][j] += x[i][k]*y[k][j];
          }
        }
      }
    }
    for(int i = 0; h > i; i++){
      x[i].resize(y.w);
    }
    w = y.w;
    for(int i = 0; h > i; i++){
      for(int j = 0; y.w > j; j++){
        x[i][j] = ret[i][j];
      }
    }
    return *this;
  }

  mat operator*(const mat& y)const{return mat(*this) *= y;}


  mat pow(long long n){//正方行列のみ
    mat<T> res(h,w);
    mat<T> ret(h,w,0);
    mat<T> a(h,w);
    for(int i = 0; h > i; i++){
      ret[i][i] = 1;
    }
    for(int i = 0; h > i; i++){
      for(int j = 0; w > j; j++){
        a[i][j] = (*this)[i][j];
      }
    }
    while(n > 0){
      if(n & 1){
        ret *= a;
      }
      a *= a;
      n/=2;
    }
    for(int i = 0; h > i; i++){
      for(int j = 0; w > j; j++){
        res[i][j] = ret[i][j];
      }
    }
    return res;
  }
};
int main(){
    mat<mint> A(1,2),B(2,2);
    mint a,b;long long n;cin>>a>>b>>n;
    B[0][0] = 0;B[0][1] = b;B[1][0] = 1;B[1][1] = a;
    A[0][0] = 0;A[0][1] = 1;
    mat<mint> C = A*B.pow(n-1);
    cout << C[0][1] << endl;
    
}