#include <stdio.h>
#include <vector>
using namespace std;

int n;
int input[10100][2];
int c[10100];
bool ps[10100];

vector<int> v[10100];
int ans;
int md;
int bi;

void dfs(int node, int depth)
{
	ps[node] = true;
	if (depth > md) {
		md = depth;
		bi = node;
	}
	for (int i = 0; i < v[node].size(); i++) {
		int j = v[node][i];
		if (!ps[j]) dfs(j, depth+ 1);
	}
}

int findmax(int node)
{
	md = 0;
	memset(ps, 0, sizeof(ps));
	dfs(node, 0);
	return bi;
}

int l[10101];

void bt(int node, int target, int depth)
{
	l[depth] = node;
	ps[node ] = true;
	if (node == target) {
		ans = l[depth/2];
		return;
	}
	for (int i = 0; i < v[node].size(); i++) {
		int j = v[node][i];
		if (!ps[j]) bt(j, target, depth+ 1);
	}
}

void solve(int v1, int v2)
{
	memset(ps, 0, sizeof(ps));
	bt(v1, v2, 0);
}

int main(void)
{
	int t;
	//freopen("b.in", "rt", stdin);
	scanf("%d", &t);
	while (t--) {
		scanf("%d", &n);
		memset(c, 0, sizeof(c));
		for (int i = 0; i < n; i++)
			v[i].clear();
		for (int i = 0; i < n-1; i++) {
			int x, y;
			scanf("%d%d",&x, &y);
			--x; --y;
			v[x].push_back(y);
			v[y].push_back(x);
		}
		int v1 = findmax(4); 
		//printf("Max Distanced to 5 is %d\n", v1+1);
		int v2 = findmax(v1);
		//printf("Max Distanced to %d is %d\n", v1+1, v2+1);
		
		solve(v1, v2);
		//printf("Best vertex is %d\n", ans + 1);
		int v3 = findmax(ans);
		ans = md;
		printf("%d\n", ans);
	}
	return 0;
}