// compile: make data
// run: ./data < data.in
#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#ifdef LOCAL
#include <debug/codeforces.h>
#define debug(x...) _debug_print(#x, x);
#else
#define debug(x...) {};
#endif
template<typename...Args> void print_(Args...args){((cout<<args<<" "),...)<<endl;}
#define rep(i,a,b) for(int i=(a);i<(int)(b);++i)
#define sz(v) ((int)(v).size())
#define print(...) print_(__VA_ARGS__);
#define INTMAX (int)(9223372036854775807)
#define INF (int)(1152921504606846976)
#define double long double
#define int long long
#define MAXN 200010

void solve() {
    int n; cin >> n;
    vector<vector<pair<int, int>>> e(n);
    rep(i, 0, n-1) {
        int u, v; cin >> u >> v; --u, --v;
        e[u].push_back({v, i+1});
        e[v].push_back({u, i+1});
    }
    vector<pair<int, int>> round(n);
    round[0] = {1, 0};
    function<void(int, int)> dfs = [&](int u, int p) {
        for (auto [v, i] : e[u]) {
            if (v == p) continue;
            if (i > round[u].second) round[v] = {round[u].first, i};
            else round[v] = {round[u].first + 1, i};
            dfs(v, u);
        }
    };
    dfs(0, -1);
    int ans = 0;
    for (auto [r, x] : round) ans = max(ans, r);
    cout << ans << endl;
}

int32_t main() {
    ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);

    int _; cin >> _;
    while (_--) solve();

    return 0;
}