#include<fstream>
#include<iostream>
#include<cstdio>
#include<vector>
#define pb push_back
using namespace std;
const int MAX_N = 100005;

vector<int> G[MAX_N];
int n;

int dnm(int k)
{
    if(G[k].size()==0)
        return 0;
    else
    {
        int max=-1, multiple=0;
        for(int i=0; i<G[k].size(); i++)
        {
            int cur=dnm(G[k][i]);
            if(cur>max)
                multiple=0, max=cur;
            else if(cur==max)
                multiple=1;
        }
        if(multiple==0)
            return max+1;
        else
            return max+2;
    }
}

int main()
{
    int T, i, a, b;
    ifstream fin("zvon.in");
    freopen("zvon.out", "w", stdout);
    fin>>T;
    while(T--)
    {
        for(i=1; i<=n; i++)
            G[i].clear();
        fin>>n;
        for(i=1; i<n; i++)
        {
            fin>>a>>b;
            G[a].pb(b);
        }
        printf("%d\n", dnm(1));
    }
    return 0;
}