#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
#define maxN 100002
using namespace std;
int t, n, i, j, sol;
bool vis[maxN];
vector < int > V[maxN];
void solve();
void write();
void read()
{
    int a, b;
    freopen("zvon.in", "r", stdin);
    freopen("zvon.out", "w", stdout);
    scanf("%d", &t);
    while (t --)
    {
        scanf("%d", &n);
        if (n == 1)
        {
            printf("%d\n", 0);
            continue;
        }
        memset(vis, 0, sizeof(vis));
        for (i = 1; i < n; ++ i)
        {
            scanf("%d %d", &a, &b);
            V[a].push_back(b);
        }
        solve();
        write();
    }
}
void dfs(int x, int y)
{
    int i, l = V[x].size(), node;
    vis[x] = 1;
    for (i = 0; i < l; ++ i)
    {
        node = V[x][i];
        if (!vis[node])
            dfs(node, y + 1);
        V[x].erase(V[x].begin() + i - 1);
    }
    sol = max(sol, y);
}
void solve()
{
    int i;
    for (i = 1; i <= n; ++ i)
        if (!vis[i])
           dfs(i, 1);
}
void write()
{
    printf("%d\n", sol);
}
int main()
{
    read();
    return 0;
}