#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; using namespace atcoder; typedef long long ll; #define rep(i, n) for (int i = 0; i < (int)(n); i++) #define repr(i, n) for (int i = (int)(n) - 1; i >= 0; i--) #define repk(i, k, n) for (int i = k; i < (int)(n); i++) #define all(v) v.begin(), v.end() #define mod1 1000000007 #define mod2 998244353 #define mod3 100000007 #define vi vector #define vs vector #define vc vector #define vl vector #define vb vector #define vvi vector> #define vvc vector> #define vvl vector> #define vvb vector> #define vvvi vector>> #define vvvl vector>> #define pii pair #define pil pair #define pli pair #define pll pair #define vpii vector> #define vpll vector> #define vvpii vector>> #define vvpll vector>> template void debug(T e) { cerr << e << endl; } template void debug(vector &v) { rep(i, v.size()) { cerr << v[i] << " "; } cerr << endl; } template void debug(vector> &v) { rep(i, v.size()) { rep(j, v[i].size()) { cerr << v[i][j] << " "; } cerr << endl; } } template void debug(vector> &v) { rep(i, v.size()) { cerr << v[i].first << " " << v[i].second << endl; } } template void debug(set &st) { for (auto itr = st.begin(); itr != st.end(); itr++) { cerr << *itr << " "; } cerr << endl; } template void debug(multiset &ms) { for (auto itr = ms.begin(); itr != ms.end(); itr++) { cerr << *itr << " "; } cerr << endl; } template void debug(map &mp) { for (auto itr = mp.begin(); itr != mp.end(); itr++) { cerr << itr->first << " " << itr->second << endl; } } void debug_out() { cerr << endl; } template void debug_out(Head H, Tail... T) { cerr << H << " "; debug_out(T...); } using mint = modint998244353; void debug_mint1(vector &vec) { for (int i = 0; i < vec.size(); i++) { cerr << vec[i].val() << " "; } cerr << endl; } void debug_mint2(vector> &vec) { for (int i = 0; i < vec.size(); i++) { for (int j = 0; j < vec[i].size(); j++) { cerr << vec[i][j].val() << " "; } cerr << endl; } } void dfs(vector> &graph, vector &isvisited, ll v, vector &treedp){ isvisited[v] = true; ll ret = 1; for (ll x: graph[v]){ if (isvisited[x]){ continue; } dfs(graph, isvisited, x, treedp); ret += treedp[x]; } treedp[v] = ret; return; } int main() { // 全通り求めてから割る ll N; cin >> N; vector u(N - 1); vector v(N - 1); for (ll i = 0; i < N - 1; i++){ cin >> u[i] >> v[i]; u[i]--; v[i]--; } vector> graph(N, vector(0)); for (ll i = 0; i < N - 1; i++){ graph[u[i]].push_back(v[i]); graph[v[i]].push_back(u[i]); } // 選び方の総通り数は、(N - 1) * binom(N, 2) 通り vector isvisited(N, false); vector treedp(N, 0); dfs(graph, isvisited, 0, treedp); mint all_val = mint(N - 1) * mint(N - 1) * mint(N) / mint(2); mint ans_val = mint(0); for (ll i = 0; i < N - 1; i++){ ll child = min(treedp[u[i]], treedp[v[i]]); ans_val += mint(child) * mint(child - 1) / mint(2); ans_val += mint(N - child) * mint(N - child - 1) / mint(2); } cout << (ans_val / all_val).val() << endl; }