#include <bits/stdc++.h>
#define Nmax 100002
#define pb(x) push_back(x)
#define Max(x, y) x > y ? x : y

FILE *fin  = freopen("zvon.in", "r", stdin);
FILE *fout = freopen("zvon.out", "w", stdout);

using namespace std;
int T, n, Time[Nmax];
bool ok;
vector <int> G[Nmax], v[Nmax];
void initialize()
{
    ok = 0;
    for(int i = 1; i <= n; ++ i)
        G[i].clear(), v[i].clear();
    memset(Time, 0, sizeof(Time));
}
int DFS(int x)
{
    int i, sz = G[x].size();
    if(sz > 0)
    {
        for(i = 0; i < sz; ++ i)
        {
            int y = G[x][i];
            DFS(y);
            v[x].pb(Time[y]);
        }
        sort(v[x].begin(), v[x].end());
        for(i = sz - 1; i >= 0; -- i)
            Time[x] = Max(Time[x], v[x][i] + sz - i);
    }
}
int main()
{
    int x, y;
    scanf("%d", &T);
    while(T --)
    {
        initialize();
        scanf("%d", &n);
        if(n == 1) ok = 1;

        for(int i = 1; i < n; ++ i)
        {
            scanf("%d %d", &x, &y);
            G[x].pb(y);
        }

        if(!ok)
        {
            DFS(1);
            printf("%d\n", Time[1]);
        }
        else printf("0\n");
    }
    return 0;
}