#ifdef LOCAL //#define _GLIBCXX_DEBUG #endif //#pragma GCC target("avx512f,avx512dq,avx512cd,avx512bw,avx512vl") #pragma GCC optimize("O3") #pragma GCC optimize("unroll-loops") #include using namespace std; typedef long long ll; typedef pair P; typedef pair Pi; typedef vector Vec; typedef vector Vi; typedef vector Vs; typedef vector Vc; typedef vector

VP; typedef vector> VV; typedef vector> VVi; typedef vector> VVc; typedef vector>> VVV; typedef vector>>> VVVV; #define REP(i, a, b) for(ll i=(a); i<(b); i++) #define PER(i, a, b) for(ll i=(a); i>=(b); i--) #define rep(i, n) REP(i, 0, n) #define per(i, n) PER(i, n, 0) const ll INF=1e18+18; const ll MOD=1000000007; #define Yes(n) cout << ((n) ? "Yes" : "No") << endl; #define YES(n) cout << ((n) ? "YES" : "NO") << endl; #define ALL(v) v.begin(), v.end() #define rALL(v) v.rbegin(), v.rend() #define pb(x) push_back(x) #define mp(a, b) make_pair(a,b) #define Each(a,b) for(auto &a :b) #define rEach(i, mp) for (auto i = mp.rbegin(); i != mp.rend(); ++i) #ifdef LOCAL #define dbg(x_) cerr << #x_ << ":" << x_ << endl; #define dbgmap(mp) cerr << #mp << ":"<first <<":"<second << endl;} #define dbgset(st) cerr << #st << ":"<bool chmax(T &a, const T &b) { if (abool chmin(T &a, const T &b) { if (b ostream &operator<<(ostream &s, const pair &p) { return s<<"("<istream& operator>>(istream&i,vector&v) {rep(j,v.size())i>>v[j];return i;} // vector template ostream &operator<<(ostream &s, const vector &v) { int len=v.size(); for(int i=0; i ostream &operator<<(ostream &s, const vector > &vv) { int len=vv.size(); for(int i=0; i= MOD) x -= MOD; return *this; } mint& operator-=(const mint a) { if ((x += MOD-a.x) >= MOD) x -= MOD; return *this; } mint& operator*=(const mint a) { (x *= a.x) %= MOD; return *this;} mint operator+(const mint a) const { return mint(*this) += a;} mint operator-(const mint a) const { return mint(*this) -= a;} mint operator*(const mint a) const { return mint(*this) *= a;} mint pow(ll t) const { if (!t) return 1; mint a = pow(t>>1); a *= a; if (t&1) a *= *this; return a; } // for prime MOD mint inv() const { return pow(MOD-2);} mint& operator/=(const mint a) { return *this *= a.inv();} mint operator/(const mint a) const { return mint(*this) /= a;} }; istream& operator>>(istream& is, const mint& a) { return is >> a.x;} ostream& operator<<(ostream& os, const mint& a) { return os << a.x;} typedef vector Vmint; struct combination { vector fact, ifact; combination(int n):fact(n+1),ifact(n+1) { assert(n < MOD); fact[0] = 1; for (int i = 1; i <= n; ++i) fact[i] = fact[i-1]*i; ifact[n] = fact[n].inv(); for (int i = n; i >= 1; --i) ifact[i-1] = ifact[i]*i; } mint operator()(int n, int k) { if (k < 0 || k > n) return 0; return fact[n]*ifact[k]*ifact[n-k]; } }; int solve(){ ll n; cin>>n; VV g(n); set st; rep(i,n){ st.insert(i); } rep(i,n-1){ ll u,v; cin>>u>>v; u--;v--; g[u].pb(v); st.erase(v); } //dbgset(st); dbg(g); ll root = *st.begin(); mint ans = 0; Vec sz(n); Vmint dp(n); auto dfs = [&](auto dfs, ll v, ll p)->ll { ll node = 1; Each(x, g[v]) { if(x != p) { node += dfs(dfs, x, v); } } return sz[v] = node; }; dfs(dfs, root, -1); dbg(sz) auto dfs2 = [&](auto dfs2, ll v, ll p)->mint { dp[v] = sz[v]-1; dbg(mp(v,dp[v])); Each(x, g[v]) { if(x != p) { dp[v] += dfs2(dfs2, x, v); } } return dp[v]; }; dfs2(dfs2, root, -1); dbg(dp) rep(i,n) ans += dp[i]; cout<