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

FILE *fout = freopen("zvon.out", "w", stdout);

using namespace std;
int T, n, Time[Nmax], v[Nmax];
bool ok;
vector <int> G[Nmax];
class InputReader
{
public:
    InputReader() {}
    InputReader(const char *file_name)
    {
        input_file = fopen(file_name, "r");
        cursor = 0;
        fread(buffer, SIZE, 1, input_file);
    }
    inline InputReader &operator >>(int &n)
    {
        while(buffer[cursor] < '0' || buffer[cursor] > '9')
        {
            advance();
        }
        n = 0;
        while('0' <= buffer[cursor] && buffer[cursor] <= '9')
        {
            n = n * 10 + buffer[cursor] - '0';
            advance();
        }
        return *this;
    }
private:
    FILE *input_file;
    static const int SIZE = 1 << 17;
    int cursor;
    char buffer[SIZE];
    inline void advance()
    {
        ++ cursor;
        if(cursor == SIZE)
        {
            cursor = 0;
            fread(buffer, SIZE, 1, input_file);
        }
    }
};
void initialize()
{
    ok = 0;
    for(int i = 1; i <= n; ++ i)
        G[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[i] = Time[y];
        }
        sort(v, v + sz - 1);
        for(i = sz - 1; i >= 0; -- i)
            Time[x] = Max(Time[x], v[i] + sz - i);
    }
}
int main()
{
    int x, y;
    InputReader cin("zvon.in");
    cin >> T;
    while(T --)
    {
        initialize();
        cin >> n;
        if(n == 1)
            ok = 1;
        /// read
        for(int i = 1; i < n; ++ i)
        {
            cin >> x >> y;
            G[x].pb(y);
        }

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