#include #include #include #include #include #include #include #include #include #include #include using namespace std; using lli = long long int; using Vint = std::vector; using Vlli = std::vector; using Wint = std::vector; using Wlli = std::vector; using Vbool = std::vector; using pii = std::pair; using pll = std::pair; template using Vec = std::vector; constexpr int MOD = 1e9 + 7; constexpr int INFi = 2e9 + 1; constexpr lli INFl = (lli)(9e18) + 1; const vector DXDY = {std::make_pair(1, 0), std::make_pair(-1, 0), std::make_pair(0, 1), std::make_pair(0, -1)}; constexpr char BR = '\n'; #define FOR(i, a, b) for(int (i) = (a); (i) < (b); (i)++) #define FOReq(i, a, b) for(int (i) = (a); (i) <= (b); (i)++) #define rFOR(i, a, b) for(int (i) = (b); (i) >= (a); i--) #define FORstep(i, a, b, step) for(int (i) = (a); i < (b); i += (step)) #define REP(i, n) FOR(i, 0, n) #define rREP(i, n) rFOR(i, 0, (n-1)) #define vREP(ele, vec) for(auto &(ele) : (vec)) #define vREPcopy(ele, vec) for(auto (ele) : (vec)) #define SORT(A) std::sort((A).begin(), (A).end()) #define rSORT(A) std::sort((A).rbegin(), (A).rend()) // 座標圧縮 (for vector) : ソートしてから使うのが一般的 ; SORT(A) => COORDINATE_COMPRESSION(A) #define COORDINATE_COMPRESSION(A) (A).erase(unique((A).begin(),(A).end()),(A).end()) template inline int argmin(std::vector vec){return min_element(vec.begin(), vec.end()) - vec.begin();} template inline int argmax(std::vector vec){return max_element(vec.begin(), vec.end()) - vec.begin();} template inline void chmax(T &a, T b){a = max(a, b);} template inline void chmin(T &a, T b){a = min(a, b);} inline int BitI(int k){return 1 << k;} inline lli BitL(int k){return 1L << k;} inline int toInt(string &s){int res = 0; for(char a : s) res = 10 * res + (a - '0'); return res;} inline int toInt(const string s){int res = 0; for(char a : s) res = 10 * res + (a - '0'); return res;} inline long long int toLong(string &s){lli res = 0; for(char a : s) res = 10 * res + (a - '0'); return res;} inline long long int toLong(const string s){lli res = 0; for(char a : s) res = 10 * res + (a - '0'); return res;} template inline std::string toString(T n){ if(n == 0) return "0"; std::string res = ""; if(n < 0){n = -n;while(n != 0){res += (char)(n % 10 + '0'); n /= 10;} std::reverse(res.begin(), res.end()); return '-' + res;} while(n != 0){res += (char)(n % 10 + '0'); n /= 10;} std::reverse(res.begin(), res.end()); return res; } // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ template struct Modlli{ using lli = long long int; lli number; // +, -, *, /, +=, -=, *=, /= が Modについて定義する inline Modlli operator +(Modlli that) const {return Modlli((this->number + that.number) % mod_number__);} inline void operator +=(Modlli that){this->number = (this->number + that.number) % mod_number__;} inline void operator ++(){this->number = (this->number + 1) % mod_number__;} inline Modlli operator -(Modlli that) const {return Modlli((this->number - that.number + mod_number__) % mod_number__);} inline void operator -=(Modlli that){this->number = (this->number + that.number + mod_number__) % mod_number__;} inline void operator --(){this->number = (this->number - 1) % mod_number__;} inline Modlli operator *(Modlli that) const {return Modlli((this->number * that.number) % mod_number__); } inline void operator *=(const Modlli that){this->number = (this->number * that.number) % mod_number__;} inline Modlli power(lli n) const { // 冪乗 : number^nを計算 lli res = 1LL, waiting = this->number; while(n != 0LL){ if((n & 1LL) != 0LL) res = (res * waiting) % mod_number__; waiting = waiting * waiting % mod_number__; n >>= 1; } return Modlli(res); } inline Modlli inv(void) const {return this->power(mod_number__ - 2);} inline Modlli operator /(Modlli that) const{ return (*this) * that.inv();} inline void operator /=(Modlli that) { lli n = mod_number__ - 2; lli res = 1LL, waiting = that.number; while(n != 0LL){ if((n & 1LL) != 0LL) res = (res * waiting) % mod_number__; waiting = waiting * waiting % mod_number__; n >>= 1; } this->snumber = (this->number * res) % MOD; } inline Modlli operator %(Modlli that){return Modlli(this->number % that.number);} inline Modlli operator %=(Modlli that){this->number %= that.number;} Modlli(lli mn){ number = mn % mod_number__;} ~Modlli(void){} //operator long long int() const {return number;} lli toLong(void) const {return number;} }; using modint = Modlli; int main(void){ int n; scanf("%d", &n);Wint Tree(n, Vint(0)); REP(_, n-1){ int a, b; scanf("%d%d", &a, &b); a--; b--; Tree[a].emplace_back(b); Tree[b].emplace_back(a); } Vbool hasDone(n, false); queue A; A.push(0); hasDone[0] = true; modint res(0); modint kaijou(1); int depth = 1; for(int i = 2; i <= n; i++) kaijou *= modint(i); while(not A.empty()){ int sz = A.size(); REP(_, sz){ int idx = A.front(); A.pop(); vREP(ele, Tree[idx]){ if(not hasDone[ele]){ hasDone[ele] = true; A.push(ele); } } } res += (modint(sz) / modint(depth)); depth++; } cout << (res * kaijou).toLong() << BR; return 0; }