/*
 * GCPC11J.cpp
 *
 *  Created on: Jun 15, 2014
 *      Author: Arpit Bhayani
 */

#include <list>
#include <climits>
#include <stack>
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <vector>

using namespace std;

#define DEBUG 0
#define gc getchar
#define ll long long

void scanint(int &x) {
    register int c = gc();
    x = 0;
    for (; (c < 48 || c > 57); c = gc())
        ;
    for (; c > 47 && c < 58; c = gc()) {
        x = (x << 1) + (x << 3) + c - 48;
    }
}

int readline(char * str) {

    int i = 0;
    char ch;
    while ((ch = getchar()) != '\n') {
        str[i++] = ch;
    }
    str[i] = '\0';
    return i;
}

#define SIZE 100001

list<int> node[SIZE];
int dfs[SIZE];

int dfs_function(int start, int n) {

    for (int i = 0; i < n; i++) {
        dfs[i] = -1;
    }

    stack<int> s;
    dfs[start] = 0;

    s.push(start);

    while (!s.empty()) {
        int parent = s.top();
        s.pop();

        for (list<int>::iterator itr = node[parent].begin();
                itr != node[parent].end(); itr++) {
            int child = *itr;

            if (dfs[child] != -1)
                continue;

            dfs[child] = dfs[parent] + 1;
            s.push(child);
        }
    }

    int max = INT_MIN;
    for (int i = 0; i < n; i++) {
        if (dfs[i] > max)
            max = dfs[i];
    }

    return max;

}

int main(int argc, char * argv[]) {

    int t;
    scanf("%d", &t);
    while (t--) {
        int n, a, b;
        //scanf("%d", &n);
        scanint(n);

        for (int i = 0; i < n; i++) {
            node[i].clear();
        }

        for (int i = 0; i < n - 1; i++) {
            //scanf("%d%d", &a, &b);
            scanint(a);
            scanint(b);
            node[a].push_back(b);
            node[b].push_back(a);
        }

        int min = INT_MAX;
        for (int i = 0; i < n; i++) {
            int max = dfs_function(i, n);
            if (max < min)
                min = max;
        }

        printf("%d\n", min);

    }
    return 0;
}