#include #include using namespace std; #define MOD 1000000007 //B template 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(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 (t); return (is); } }; using mint = ModInt; template struct mat{ vector> x; int h,w; mat():x(vector>()){} mat(int h,int w):x(vector>(h,vector(w))),h(h),w(w){} mat(int h,int w, T c):x(vector>(h,vector(w,c))),h(h),w(w){} vector operator[](const int i)const{return x[i];} vector& operator[](const int i){return x[i];} mat& operator*=(const mat& y){ mat 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 res(h,w); mat ret(h,w,0); mat 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 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 C = A*B.pow(n-1); cout << C[0][1] << endl; }