#include <fstream>
#include <vector>
#include <bitset>
#include <queue>
#include <algorithm>
#include <utility>
#include <cstring>
#include <string>
#include <stack>
#include <deque>
#include <iomanip>
#include <set>
#include <map>
#include <cassert>
#include <ctime>

using namespace std;

ifstream cin("zvon.in");
ofstream cout("zvon.out");

const int MAXN = 100005;
const int oo = (1<<31)-1;

typedef vector<int> Graph[MAXN];
typedef vector<int> :: iterator It;

const inline int min(const int &a, const int &b) { if( a > b ) return b;   return a; }
const inline int max(const int &a, const int &b) { if( a < b ) return b;   return a; }
const inline void Get_min(int &a, const int b)    { if( a > b ) a = b; }
const inline void Get_max(int &a, const int b)    { if( a < b ) a = b; }

int T, N, Time[MAXN];

struct ClassComp {
    inline bool operator () (const int &a, const int &b) const {
        return Time[a] > Time[b];
    }
};

inline void DFs(int Node, Graph &G) {
    Time[Node] = 0;
    for(It it = G[Node].begin(), fin = G[Node].end() ; it != fin ; ++ it)
        DFs(*it, G);
    sort(G[Node].begin(), G[Node].end(), ClassComp());
    int x = 0;
    for(It it = G[Node].begin(), fin = G[Node].end() ; it != fin ; ++ it, ++ x)
        Time[Node] = max(Time[Node], Time[*it] + x + 1);
}

int main() {
    for(cin >> T, cin >> N ; T ; -- T, cin >> N) {
        Graph G;
        for(int i = 1, x, y ; i != N ; ++ i) {
            cin >> x >> y;
            G[x].push_back(y);
        }
        DFs(1, G);
        cout << Time[1] << '\n';
    }
    cin.close();
    cout.close();
    return 0;
}