#include <stdio.h>
#include <vector>
#include <algorithm>
#include <utility>
using namespace std;

#define in "zvon.in"
#define out "zvon.out"
#define dim 100067

int T, N, Q;
int Vec[dim];
bool Sel[dim], Selq[dim];
vector<int> L[dim];

int Tmin[dim];
vector<int> R;

struct Compare {
       bool operator() (int i, int j)
       {
            return R[i] > R[j];
       }
};

inline int Maxim(int a, int b ) { return a > b ? a : b; }

void DF(int);
void Solve(int,int);
void DF_Solve(int nod);

int main()
{
    int X, Y;
    
    freopen(in,"r",stdin);
    freopen(out,"w",stdout);
    
    scanf("%d", &T);
    for ( ; T > 0; T-- )
    {
        scanf("%d", &N);
        for ( int i = 1; i <= N; i++ ) L[i].clear(), Tmin[i] = 0; 
        
        for ( int i = 1; i < N; i++ )
        {
            scanf("%d%d", &X, &Y);
            L[X].push_back(Y);
        }
        
        DF_Solve(1);
        
      /*  for ( int i = 1; i <= N; i++ )
            printf("%d ", Tmin[i] );
            */
        printf("%d\n", Tmin[1]);
        
       // printf("\n");
    }
}

void DF_Solve(int nod)
{
     if ( L[nod].size() == 0 ) 
     {
          Tmin[nod] = 0;
          return;
     }
     
     for ( int i = 0; i < L[nod].size(); i++ )
     {
         DF_Solve(L[nod][i]);
     }
     
     R.clear();
     
     for ( int i = 0; i < L[nod].size(); i++ )
     {
         R.push_back(Tmin[L[nod][i]]);
     } 
     
    /* printf("|");
     
     sort( R.begin(), R.end(), Compare()  );
     
     for ( int i = 0; i < R.size(); i++ )
     {
       //  printf("%d ", R[i]);
         Tmin[nod] = Maxim( Tmin[nod], i+1+R[i] ); 
     }
     
    // printf(" %d\n", L[nod].size() );*/
}
/*
void DF(int nod)
{
     if ( L[nod].size() == 0 ) Vec[nod] = 0; 
     
     for ( int i = 0; i < L[nod].size(); i++ )
     {
         DF(L[nod][i]);
         
         Vec[nod] += Vec[L[nod][i]] + 1;
     }
}

void Solve(int nod, int timp)
{
     if ( Q < timp ) Q = timp;
     
     for ( int i = 0; i < L[nod].size(); i++ )
     {
         Solve(L[nod][i],timp+1+i);
     }
}*/