#include <iostream>
#include <fstream>
#include <vector>
#include <cstring>
#include <algorithm>
using namespace std;
ifstream fin("zvon.in");
ofstream fout("zvon.out");
const int Nmax=100005;
vector <int> G[Nmax];
int N,ap[Nmax],PI,dp[Nmax],T;
void read()
{
    fin>>N;
    for(int i=1;i<=N;i++)
    {
        G[i].erase(G[i].begin(),G[i].end());
    }
    memset(ap,0,sizeof(ap));
    for(int i=1;i<N;i++)
    {
        int x,y;
        fin>>x>>y;
        G[x].push_back(y);
        ap[y]=1;
    }
    for(int i=1;i<=N;i++)
    {
        if(!ap[i])
        {
            PI=i;
            break;
        }
    }
}
int comp(int a,int b)
{
    return a>b;
}
void DFS(int nod)
{
    dp[nod]=0;
    vector <int> V;
    for(int i=0;i<G[nod].size();i++)
    {
        int son=G[nod][i];
        DFS(son);
        V.push_back(dp[son]);
    }
    sort(V.begin(),V.end(),comp);
    for(int i=1;i<=V.size();i++)
    {
        if(dp[nod]<V[i-1]+i)
        {
            dp[nod]=V[i-1]+i;
        }
    }
}



void solve()
{
    DFS(PI);
    fout<<dp[PI]<<"\n";
}

int main()
{
    fin>>T;
    while(T--)
    {
        read();
        solve();
    }
    return 0;
}