#ifdef stderr_path #define LOCAL #define _GLIBCXX_DEBUG #endif #pragma GCC optimize("Ofast") #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define debug_stream std::cerr #define iostream_untie true #define __precision__ 10 #define rep(i, n) for(int i = 0; i < int(n); ++i) #define all(v) begin(v), end(v) #define rall(v) rbegin(v), rend(v) #define odd(n) (int_fast64_t(n) & 1LL) #define even(n) (odd(n) ^ 1LL) #define bit(n, i) (int_fast64_t(n) >> size_t(i) & 1LL) #define mask(n, i) (int_fast64_t(n) & (1LL << size_t(i)) - 1) #define mkp make_pair #define mkt make_tuple #define popcnt __builtin_popcountll using i64 = int_fast64_t; using pii = std::pair; using pll = std::pair; template using heap = std::priority_queue; template using minheap = std::priority_queue, std::greater>; template constexpr T inf = std::numeric_limits::max() / (T)2 - (T)1123456; constexpr int dx[9] = {1, 0, -1, 0, 1, -1, -1, 1, 0}; constexpr int dy[9] = {0, 1, 0, -1, 1, 1, -1, -1, 0}; namespace execution { std::chrono::system_clock::time_point start_time, end_time; void print_elapsed_time() { end_time = std::chrono::system_clock::now(); std::cerr << "\n----- Exec time : "; std::cerr << std::chrono::duration_cast(end_time - start_time).count(); std::cerr << " ms -----\n\n"; } struct setupper { setupper() { if(iostream_untie) { std::ios::sync_with_stdio(false); std::cin.tie(nullptr); } std::cout << std::fixed << std::setprecision(__precision__); #ifdef stderr_path if(freopen(stderr_path, "a", stderr)) { std::cerr << std::fixed << std::setprecision(__precision__); } else fclose(stderr); #endif #ifdef stdout_path if(not freopen(stdout_path, "w", stdout)) { freopen("CON", "w", stdout); std::cerr << "Failed to open the stdout file\n\n"; } std::cout << ""; #endif #ifdef stdin_path if(not freopen(stdin_path, "r", stdin)) { freopen("CON", "r", stdin); std::cerr << "Failed to open the stdin file\n\n"; } #endif #ifdef LOCAL atexit(print_elapsed_time); start_time = std::chrono::system_clock::now(); #endif } } __setupper; } struct myclock_t { std::chrono::system_clock::time_point built_pt, last_pt; int built_ln, last_ln; std::string built_func, last_func; bool is_built; myclock_t() : is_built(false) {} void build(int crt_ln, const std::string &crt_func) { is_built = true; last_pt = built_pt = std::chrono::system_clock::now(); last_ln = built_ln = crt_ln, last_func = built_func = crt_func; } void set(int crt_ln, const std::string &crt_func) { if(is_built) { last_pt = std::chrono::system_clock::now(); last_ln = crt_ln, last_func = crt_func; } else { debug_stream << "[ " << crt_ln << " : " << crt_func << " ] " << "myclock_t::set failed (yet to be built clock!)\n"; } } void get(int crt_ln, const std::string &crt_func) { if(is_built) { std::chrono::system_clock::time_point crt_pt(std::chrono::system_clock::now()); int64_t diff = std::chrono::duration_cast(crt_pt - last_pt).count(); debug_stream << diff << " ms elapsed from" << " [ " << last_ln << " : " << last_func << " ]"; if(last_ln == built_ln) debug_stream << " (when built)"; debug_stream << " to" << " [ " << crt_ln << " : " << crt_func << " ]" << "\n"; last_pt = built_pt, last_ln = built_ln, last_func = built_func; } else { debug_stream << "[ " << crt_ln << " : " << crt_func << " ] " << "myclock_t::get failed (yet to be built clock!)\n"; } } }; #ifdef LOCAL myclock_t myclock; #define build_clock() myclock.build(__LINE__, __func__) #define set_clock() myclock.set(__LINE__, __func__) #define get_clock() myclock.get(__LINE__, __func__) #else #define build_clock() #define set_clock() #define get_clock() #endif namespace std { template void rsort(RAitr __first, RAitr __last) { sort(__first, __last, greater<>()); } template size_t hash_combine(size_t seed, T const &key) { return seed ^ (hash()(key) + 0x9e3779b9 + (seed << 6) + (seed >> 2)); } template struct hash> { size_t operator()(pair const &pr) const { return hash_combine(hash_combine(0, pr.first), pr.second); } }; template ::value - 1> struct tuple_hash_calc { static size_t apply(size_t seed, tuple_t const &t) { return hash_combine(tuple_hash_calc::apply(seed, t), get(t)); } }; template struct tuple_hash_calc { static size_t apply(size_t seed, tuple_t const &t) { return hash_combine(seed, get<0>(t)); } }; template struct hash> { size_t operator()(tuple const &t) const { return tuple_hash_calc>::apply(0, t); } }; template istream &operator>> (std::istream &s, pair &p) { return s >> p.first >> p.second; } template ostream &operator<< (std::ostream &s, const pair p) { return s << p.first << " " << p.second; } template istream &operator>> (istream &s, vector &v) { for(T &e : v) { s >> e; } return s; } template ostream &operator<< (ostream &s, const vector &v) { for(size_t i = 0; i < v.size(); ++i) { s << (i ? " " : "") << v[i]; } return s; } template struct tupleos { static ostream &apply(ostream &s, const tuple_t &t) { tupleos::apply(s,t); return s << " " << get(t); } }; template struct tupleos { static ostream &apply(ostream &s, const tuple_t &t) { return s << get<0>(t); } }; template ostream &operator<< (ostream &s, const tuple &t) { return tupleos, tuple_size>::value - 1>::apply(s,t); } template <> ostream &operator<< (ostream &s, const tuple<> &t) { return s; } } #ifdef LOCAL #define dump(...) debug_stream << " [ " << __LINE__ << " : " << __FUNCTION__ << " ] " << #__VA_ARGS__ << " : ", dump_func(__VA_ARGS__) #else #define dump(...) #endif template void dump_func(const T &x) { debug_stream << x << '\n'; } template void dump_func(const T &x, Rest ... rest) { debug_stream << x << ", "; dump_func(rest...); } template void write(const T &x) { std::cout << x << '\n'; } template void write(const T &x, Rest ... rest) { std::cout << x << ' '; write(rest...); } void writeln() {} template void writeln(const T &x, Rest ... rest) { std::cout << x << '\n'; writeln(rest...); } #define esc(...) writeln(__VA_ARGS__), exit(0) template void read_range(P __first, P __second) { for(P i = __first; i != __second; ++i) std::cin >> *i; } template bool chmin(T &x, const T &y) { return x > y ? x = y, true : false; } template bool chmax(T &x, const T &y) { return x < y ? x = y, true : false; } template constexpr T minf(const T &x, const T &y) { return std::min(x,y); } template constexpr T maxf(const T &x, const T &y) { return std::max(x,y); } template int_t bin(int_t ok, int_t ng, const F &f) { while (std::abs(ok - ng) > 1) { int_t mid = (ok + ng) / 2; (f(mid) ? ok : ng) = mid; } return ok; } template void init(A (&array)[N], const T &val) { std::fill((T*)array, (T*)(array + N), val); } template void init(A (&array)[N]) { memset(array, 0, sizeof(array)); } void for_subset(int_fast64_t s, const std::function &fn) { int_fast64_t t = s; do { fn(t); } while((--t &= s) != s); } namespace math { template constexpr int_t gcd(int_t x, int_t y) { x = x > 0 ? x : -x, y = y > 0 ? y : -y; while(y) y ^= x ^= y ^= x %= y; return x; } template constexpr int_t lcm(int_t x, int_t y) { return x ? x / gcd(x, y) * y : 0; } template constexpr std::pair ext_gcd(int_t a, int_t b) { int_t sgn_a = a >= 0, sgn_b = b >= 0; int_t p = 1, q = 0, r = 0, s = 1; while(b) { int_t t = a / b; r ^= p ^= r ^= p -= t * r; s ^= q ^= s ^= q -= t * s; b ^= a ^= b ^= a %= b; } return std::pair(sgn_a ? p : -p, sgn_b ? q : -q); } } /* The main code follows. */ signed main() { void solve(); void input(); void init(); int t = 1; // cin >> t; while(t--) { init(); input(); solve(); } } using namespace std; using namespace math; template struct modint { int x; constexpr modint() : x(0) {} constexpr modint(int_fast64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {} constexpr modint &operator+=(const modint &p) { if((x += p.x) >= mod) x -= mod; return *this; } constexpr modint &operator++() { return ++x, *this; } constexpr modint operator++(int) { modint t = *this; return ++x, t; } constexpr modint &operator-=(const modint &p) { if((x += mod - p.x) >= mod) x -= mod; return *this; } constexpr modint &operator--() { return --x, *this; } constexpr modint operator--(int) { modint t = *this; return --x, t; } constexpr modint &operator*=(const modint &p) { return x = (int_fast64_t)x * p.x % mod, *this; } constexpr modint &operator/=(const modint &p) { return *this *= inverse(p); } // constexpr modint &operator%=(int m) { return x %= m, *this; } constexpr modint operator-() const { return modint(-x); } constexpr modint operator+(const modint &p) const { return modint(*this) += p; } constexpr modint operator-(const modint &p) const { return modint(*this) -= p; } constexpr modint operator*(const modint &p) const { return modint(*this) *= p; } constexpr modint operator/(const modint &p) const { return modint(*this) /= p; } // constexpr modint operator%(int m) const { return modint(*this) %= m; } constexpr bool operator==(const modint &p) const { return x == p.x; } constexpr bool operator!=(const modint &p) const { return x != p.x; } constexpr bool operator!() const { return !x; } // constexpr bool operator>(const modint &p) const { return x > p.x; } // constexpr bool operator<(const modint &p) const { return x < p.x; } // constexpr bool operator>=(const modint &p) const { return x >= p.x; } // constexpr bool operator<=(const modint &p) const { return x <= p.x; } constexpr friend modint inverse(const modint &p) { int a = p.x, b = mod, u = 1, v = 0; while(b > 0) { int t = a / b; a -= t * b; a ^= b ^= a ^= b; u -= t * v; u ^= v ^= u ^= v; } return modint(u); } constexpr friend modint pow(modint p, int_fast64_t e) { if(e < 0) e = (e % (mod - 1) + mod - 1) % (mod - 1); modint ret = 1; while(e) { if(e & 1) ret *= p; p *= p; e >>= 1; } return ret; } friend ostream &operator<<(ostream &s, const modint &p) { return s << p.x; } friend istream &operator>>(istream &s, modint &p) { int_fast64_t x; p = modint((s >> x, x)); return s; } }; using mint=modint<1000000007>; int n; std::vector g[1<<18]; void init() {} void input() { std::cin >> n; for(int i=1; i> a >> b; a--, b--; g[a].emplace_back(b); g[b].emplace_back(a); } } void solve() { queue> que; que.emplace(0,-1,1); mint ans=0; while(not que.empty()) { int v,p,d; tie(v,p,d)=que.front(); que.pop(); ans+=inverse(mint(d)); for(int u : g[v]) { if(u!=p) { que.emplace(u,v,d+1); } } } for(int i=1; i<=n; i++) { ans*=i; } std::cout << ans << '\n'; }