#include<bits/stdc++.h>
#define ios ios::sync_with_stdio(0), cin.tie(0)
#define time chrono::system_clock::now().time_since_epoch().count()
using namespace std;
#define int long long
using ll = long long;
using pll = pair<int, int>;

const int mod = 998244353, N = 2e5 + 10;

int qmi(int a, int b) {
    int res = 1;
    while (b) {
        if (b & 1) res = res * a % mod;
        a = a * a % mod;
        b >>= 1;
    }
    return res;
}

using int64_t = long long;
template<const int T>
struct ModInt {
    const static int mod = T;
    int x;
    ModInt(int x = 0) : x(x % mod) {}
    int val() { return x; }
    ModInt operator + (const ModInt &a) const { int x0 = x + a.x; return ModInt(x0 < mod ? x0 : x0 - mod); }
    ModInt operator - (const ModInt &a) const { int x0 = x - a.x; return ModInt(x0 < 0 ? x0 + mod : x0); }
    ModInt operator * (const ModInt &a) const { return ModInt(1LL * x * a.x % mod); }
    ModInt operator / (const ModInt &a) const { return *this * a.inv(); }
    bool operator == (const ModInt &a) const { return x == a.x; };
    bool operator != (const ModInt &a) const { return x != a.x; };
    void operator += (const ModInt &a) { x += a.x; if (x >= mod) x -= mod; }
    void operator -= (const ModInt &a) { x -= a.x; if (x < 0) x += mod; }
    void operator *= (const ModInt &a) { x = 1LL * x * a.x % mod; }
    void operator /= (const ModInt &a) { *this = *this / a; }
    friend ModInt operator + (int y, const ModInt &a){ int x0 = y + a.x; return ModInt(x0 < mod ? x0 : x0 - mod); }
    friend ModInt operator - (int y, const ModInt &a){ int x0 = y - a.x; return ModInt(x0 < 0 ? x0 + mod : x0); }
    friend ModInt operator * (int y, const ModInt &a){ return ModInt(1LL * y * a.x % mod);}
    friend ModInt operator / (int y, const ModInt &a){ return ModInt(y) / a;}
    friend ostream &operator<<(ostream &os, const ModInt &a) { return os << a.x;}
    friend istream &operator>>(istream &is, ModInt &t){return is >> t.x;}

    ModInt pow(int64_t n) const {
        ModInt res(1), mul(x);
        while(n){
            if (n & 1) res *= mul;
            mul *= mul;
            n >>= 1;
        }
        return res;
    }
    
    ModInt inv() const {
        int a = x, b = mod, u = 1, v = 0;
        while (b) {
            int t = a / b;
            a -= t * b; swap(a, b);
            u -= t * v; swap(u, v);
        }
        if (u < 0) u += mod;
        return u;
    }
    
};
using mint = ModInt<mod>;

void solve(){
    int n; cin >> n;
    vector edg(n + 10, vector<int>());
    for (int i = 1; i < n; i ++) {
        int u, v; cin >> u >> v;
        edg[u].push_back(v);
        edg[v].push_back(u);
    }

    vector<mint> sz(n + 10, 0);
    vector<mint> sum(n + 10, 0), tot(n + 10, 0);
    mint res = 0;
    function<void(int, int)> dfs1 = [&] (int u, int p) {
        sz[u] = 1;
        for (auto v : edg[u]) {
            if (v == p) continue;
            dfs1(v, u);
            sz[u] += sz[v];
            sum[u] = sum[u] + sz[v] * sz[v];
            tot[u] += sum[v];
        }
        sum[u] = sum[u] + sz[u] * sz[u];
    };
    function<void(int, int)> dfs2 = [&] (int u, int p) {
        for (auto v : edg[u]) {
            if (p == v) continue;
            res += sz[v] * sz[v] * (n - sz[v]) * (n - sz[v]);
            res += 2 * (n - sz[v]) * (n - sz[v]) * (sum[v] - sz[v] * sz[v]);
            res += sum[v] * (tot[u] - sum[v]);
            dfs2(v, u);
        }
    };
    dfs1(1, 0);
    dfs2(1, 0);
    int t = n * n % mod * (n - 1) % mod * (n - 1) % mod * qmi(4, mod - 2) % mod;
    res = res * qmi(t, mod - 2);
    cout << res << '\n';
}

signed main()
{
    ios;
    int t = 1;
    cin >> t;
    while (t--)
        solve();
    return 0;
}

answer.code:21:7: error: conflicting declaration ‘using int64_t = long long int’
   21 | using int64_t = long long;
      |       ^~~~~~~
In file included from /usr/include/x86_64-linux-gnu/sys/types.h:155,
                 from /usr/include/stdlib.h:394,
                 from /usr/include/c++/13/cstdlib:79,
                 from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:42,
                 from answer.code:1:
/usr/include/x86_64-linux-gnu/bits/stdint-intn.h:27:19: note: previous declaration as ‘typedef __int64_t int64_t’
   27 | typedef __int64_t int64_t;
      |                   ^~~~~~~