#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; template struct modint { private: unsigned int value; static constexpr int mod() {return m;} public: constexpr modint(const long long x = 0) noexcept { long long y = x; if(y < 0 || y >= mod()) { y %= mod(); if(y < 0) y += mod(); } value = (unsigned int)y; } constexpr unsigned int val() noexcept {return value;} constexpr modint &operator+=(const modint &other) noexcept { value += other.value; if(value >= mod()) value -= mod(); return *this; } constexpr modint &operator-=(const modint &other) noexcept { unsigned int x = value; if(x < other.value) x += mod(); x -= other.value; value = x; return *this; } constexpr modint &operator*=(const modint &other) noexcept { unsigned long long x = value; x *= other.value; value = (unsigned int) (x % mod()); return *this; } constexpr modint &operator/=(const modint &other) noexcept { return *this *= other.inverse(); } constexpr modint inverse() const noexcept { assert(value); long long a = value,b = mod(),x = 1,y = 0; while(b) { long long q = a/b; a -= q*b; swap(a,b); x -= q*y; swap(x,y); } return modint(x); } constexpr modint power(long long N) const noexcept { assert(N >= 0); modint p = *this,ret = 1; while(N) { if(N & 1) ret *= p; p *= p; N >>= 1; } return ret; } constexpr modint operator+() {return *this;} constexpr modint operator-() {return modint() - *this;} constexpr modint &operator++(int) noexcept {return *this += 1;} constexpr modint &operator--(int) noexcept {return *this -= 1;} friend modint operator+(const modint& lhs, const modint& rhs) {return modint(lhs) += rhs;} friend modint operator-(const modint& lhs, const modint& rhs) {return modint(lhs) -= rhs;} friend modint operator*(const modint& lhs, const modint& rhs) {return modint(lhs) *= rhs;} friend modint operator/(const modint& lhs, const modint& rhs) {return modint(lhs) /= rhs;} friend ostream &operator<<(ostream &os,const modint &x) {return os << x.value;} }; using mint = modint<998244353>; //using mint = modint<1000000007>; int N,ch[1 << 17],U[1 << 17],V[1 << 17]; vector G[1 << 17]; void dfs(int u,int p) { ch[u] = 1; for(int v:G[u]) if(v != p) { dfs(v,u); ch[u] += ch[v]; } } void solve() { cin >> N; for(int i = 1;i < N;i++) { int u,v; cin >> u >> v; u--; v--; U[i] = u,V[i]= v; G[u].push_back(v); G[v].push_back(u); } dfs(0,-1); mint ans = 0; for(int i = 1;i < N;i++) { int u = U[i],v = V[i]; if(ch[u] > ch[v]) swap(u,v); ans += 1-mint(ch[u])*(N-ch[u])*2/N/(N-1); } ans /= N-1; cout << ans << endl; } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); int tt = 1; //cin >> tt; while(tt--) solve(); }