#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...)); } template class modint { using u32 = std::uint_fast32_t; using u64 = std::uint_fast64_t; using i64 = std::int_fast64_t; public: u64 a; constexpr modint() noexcept : a(0) {} constexpr modint(const u64 & x) noexcept : a(x % Modulus) {} constexpr u64 &value() noexcept { return a; } constexpr const u64 &value() const noexcept { return a; } const modint inverse() const { i64 x = a, b = Modulus, u = 1, v = 0; while(b > 0) { auto t = x / b; std::swap(x -= t * b, b); std::swap(u -= t * v, v); } return modint(u); } const modint pow(i64 k) const { return modint(*this) ^ k; } static u64 mod() { return Modulus; } constexpr modint & operator+=(const modint & rhs) noexcept { a += rhs.a; if (a >= Modulus) a -= Modulus; return *this; } constexpr modint & operator-=(const modint & rhs) noexcept { if (a < rhs.a) a += Modulus; a -= rhs.a; return *this; } constexpr modint & operator*=(const modint & rhs) noexcept { a = a * rhs.a % Modulus; return *this; } constexpr modint & operator/=(modint rhs) noexcept { u64 exp = Modulus - 2; while (exp) { if (exp % 2) (*this) *= rhs; rhs *= rhs; exp /= 2; } return *this; } constexpr modint & operator^=(u64 k) noexcept { auto b = modint(1); while(k) { if(k & 1) b = b * (*this); (*this) *= (*this); k >>= 1; } return (*this) = b; } constexpr modint & operator=(const modint & rhs) noexcept { a = rhs.a; return (*this); } constexpr modint operator+(const modint & rhs) const noexcept { return modint(*this) += rhs; } constexpr modint operator-(const modint & rhs) const noexcept { return modint(*this) -= rhs; } constexpr modint operator*(const modint & rhs) const noexcept { return modint(*this) *= rhs; } constexpr modint operator/(const modint & rhs) const noexcept { return modint(*this) /= rhs; } constexpr modint operator^(const u64 & k) const noexcept { return modint(*this) ^= k; } constexpr modint operator-() const noexcept { return modint(Modulus - a); } constexpr modint operator++() noexcept { return (*this) = modint(*this) + 1; } constexpr modint operator--() noexcept { return (*this) = modint(*this) - 1; } const bool operator==(const modint & rhs) const noexcept { return a == rhs.a; }; const bool operator!=(const modint & rhs) const noexcept { return a != rhs.a; }; const bool operator<=(const modint & rhs) const noexcept { return a <= rhs.a; }; const bool operator>=(const modint & rhs) const noexcept { return a >= rhs.a; }; const bool operator<(const modint & rhs) const noexcept { return a < rhs.a; }; const bool operator>(const modint & rhs) const noexcept { return a > rhs.a; }; explicit operator bool() const { return a; } explicit operator u32() const { return a; } friend std::ostream & operator<<(std::ostream & os, const modint & p) { return os << p.a; } friend std::istream & operator>>(std::istream & is, modint & p) { u64 t; is >> t; p = modint(t); return is; } }; 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; } }; using mint = modint<(int)(1e9 + 7)>; 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; }