#include using namespace std; template bool cmin(A& a, B b) { return a > b && (a = b, true); } template bool cmax(A& a, B b) { return a < b && (a = b, true); } template class modint { private: unsigned int v; static unsigned int norm(const unsigned int& x) { return x < mod ? x : x - mod; } static modint make(const unsigned int& x) { modint m; return m.v = x, m; } static modint inv(const modint& x) { return make(inverse(x.v, mod)); } static unsigned int inverse(int a, int m) { int u[] = {a, 1, 0}, v[] = {m, 0, 1}, t; while (*v) { t = *u / *v; swap(u[0] -= t * v[0], v[0]), swap(u[1] -= t * v[1], v[1]), swap(u[2] -= t * v[2], v[2]); } return (u[1] % m + m) % m; } public: modint() : v{0} {} modint(const long val) : v{norm(val % mod + mod)} {} modint(const modint& n) : v{n()} {} explicit operator bool() const noexcept { return v != 0; } bool operator!() const noexcept { return !static_cast(*this); } modint& operator=(const modint& n) { return v = n(), (*this); } modint& operator=(const long val) { return v = norm(val % mod + mod), (*this); } modint operator+() const { return *this; } modint operator-() const { return v == 0 ? make(0) : make(mod - v); } modint operator+(const modint& val) const { return make(norm(v + val())); } modint operator-(const modint& val) const { return make(norm(v + mod - val())); } modint operator*(const modint& val) const { return make((long)v * val() % mod); } modint operator/(const modint& val) const { return *this * inv(val); } modint& operator+=(const modint& val) { return *this = *this + val; } modint& operator-=(const modint& val) { return *this = *this - val; } modint& operator*=(const modint& val) { return *this = *this * val; } modint& operator/=(const modint& val) { return *this = *this / val; } modint operator+(const long val) const { return modint{v + val}; } modint operator-(const long val) const { return modint{v - val}; } modint operator*(const long val) const { return modint{(long)(v * (val % mod))}; } modint operator/(const long val) const { return modint{(long)v * inv(val)}; } modint& operator+=(const long val) { return *this = *this + val; } modint& operator-=(const long val) { return *this = *this - val; } modint& operator*=(const long val) { return *this = *this * val; } modint& operator/=(const long val) { return *this = *this / val; } bool operator==(const modint& val) const { return v == val.v; } bool operator!=(const modint& val) const { return !(*this == val); } bool operator==(const long val) const { return v == norm(val % mod + mod); } bool operator!=(const long val) const { return !(*this == val); } unsigned int operator()() const { return v; } friend modint operator+(const long val, const modint& n) { return n + val; } friend modint operator-(const long val, const modint& n) { return modint{val - n()}; } friend modint operator*(const long val, const modint& n) { return n * val; } friend modint operator/(const long val, const modint& n) { return modint{val} / n; } friend bool operator==(const long val, const modint& n) { return n == val; } friend bool operator!=(const long val, const modint& n) { return !(val == n); } friend istream& operator>>(istream& is, modint& n) { unsigned int v; return is >> v, n = v, is; } friend ostream& operator<<(ostream& os, const modint& n) { return (os << n()); } friend modint mod_pow(modint x, long n) { modint ans = 1; while (n) { if (n & 1) ans *= x; x *= x, n >>= 1; } return ans; } }; constexpr int MOD = 1000000007; // constexpr int MOD = 998244353; using mint = modint; signed main() { cin.tie(nullptr)->sync_with_stdio(false); int N; cin >> N; vector> DP(N + 1, vector(4)); DP.at(0).at(0) = 1; for (int i = 0; i < N; i++) { for (int j = 0; j < 4; j++) { for (int k = 0; k < 4; k++) { if (j == k) continue; DP.at(i + 1).at(k) += DP.at(i).at(j); } } } cout << DP.back().at(0) << '\n'; }