#include using namespace std::literals::string_literals; using i64 = long long; using std::cout; using std::endl; using std::cin; template std::vector make_v(size_t a){return std::vector(a);} template auto make_v(size_t a,Ts... ts){ return std::vector(ts...))>(a,make_v(ts...)); } using namespace std; template< int mod > struct ModInt { int x; ModInt() : x(0) {} ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {} ModInt &operator+=(const ModInt &p) { if((x += p.x) >= mod) x -= mod; return *this; } ModInt &operator-=(const ModInt &p) { if((x += mod - p.x) >= mod) x -= mod; return *this; } ModInt &operator*=(const ModInt &p) { x = (int) (1LL * x * p.x % mod); return *this; } ModInt &operator/=(const ModInt &p) { *this *= p.inverse(); return *this; } ModInt operator-() const { return ModInt(-x); } 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 x == p.x; } bool operator!=(const ModInt &p) const { return x != p.x; } ModInt inverse() const { int a = x, b = mod, u = 1, v = 0, t; while(b > 0) { t = a / b; swap(a -= t * b, b); swap(u -= t * v, v); } return ModInt(u); } ModInt pow(int64_t n) const { ModInt ret(1), mul(x); while(n > 0) { if(n & 1) ret *= mul; mul *= mul; n >>= 1; } return ret; } friend ostream &operator<<(ostream &os, const ModInt &p) { return os << p.x; } friend istream &operator>>(istream &is, ModInt &a) { int64_t t; is >> t; a = ModInt< mod >(t); return (is); } static int get_mod() { return mod; } }; using modint = ModInt<(int)(1e9 + 7)>; template class square_matrix { using value_type = T; using i64 = int64_t; std::vector> data; public: square_matrix() {} square_matrix(const size_t & n) : data(n, std::vector(n, T())) {} static const square_matrix E(const size_t & n) { square_matrix e(n); for(size_t i = 0; i < n; i++) e[i][i] = 1; return e; } static const square_matrix O(const size_t & n) { return square_matrix(n); } const size_t height() const { return data.size(); } const size_t width() const { return data.size(); } const T determinant() const { square_matrix B(*this); T ret = 1; for(int i = 0; i < width(); i++) { int ind = -1; for(int j = i; j < width(); j++) { if(B[j][i] == 0) continue; ind = j; } if(ind == -1) return 0; if(i != ind) { ret *= -1; std::swap(B[i], B[ind]); } ret *= B[i][i]; for(int j = 0; j < width(); j++) B[i][j] /= B[i][i]; for(int j = i + 1; j < width(); j++) for(int k = 0; k < width(); k++) B[j][k] -= B[i][k] * B[j][i]; } return ret; } const std::vector & operator[](const size_t & k) const { return data.at(k); } std::vector & operator[](const size_t & k) { return data.at(k); } square_matrix & operator+=(const square_matrix & B) { assert(height() == B.height()); for(int i = 0; i < height(); i++) for(int j = 0; j < width(); j++) (*this)[i][j] += B[i][j]; return (*this); } square_matrix & operator-=(const square_matrix & B) { assert(height() == B.height()); for(int i = 0; i < height(); i++) for(int j = 0; j < width(); j++) (*this)[i][j] -= B[i][j]; return (*this); } square_matrix & operator*=(const square_matrix & B) { assert(height() == B.height()); auto C = square_matrix::O(height()); for(int i = 0; i < height(); i++) for(int j = 0; j < width(); j++) for(int k = 0; k < height(); k++) C[i][j] = (C[i][j] + (*this)[i][k] * B[k][j]); return (*this) = C; } square_matrix & operator^=(i64 k) { auto B = square_matrix::E(height()); while(k) { if(k & 1) B *= (*this); (*this) *= (*this); k >>= 1; } return (*this) = B; } square_matrix & operator=(const square_matrix & B) { (*this).data = B.data; return (*this); } const square_matrix operator+(const square_matrix & B) const { return (square_matrix(*this) += B); } const square_matrix operator-(const square_matrix & B) const { return (square_matrix(*this) -= B); } const square_matrix operator*(const square_matrix & B) const { return (square_matrix(*this) *= B); } const square_matrix operator^(const i64 & k) const { return (square_matrix(*this) ^= k); } const bool operator==(const square_matrix & B) const { return (data == B.data); } friend std::ostream & operator<<(std::ostream & os, square_matrix & p) { for(int i = 0; i < height(); i++) { os << "["; for(int j = 0; j < width(); j++) { os << p[i][j] << (j + 1 == width() ? "]\n" : ", "); } } return os; } }; int main() { int a, b, n; scanf("%d%d%d", &a, &b, &n); if(n == 0) { printf("0\n"); return 0; } square_matrix A(2); A[0][0] = a; A[0][1] = b; A[1][0] = 1; A ^= n - 1; printf("%d\n", A[0][0]); return 0; }