#define _CRT_SECURE_NO_WARNINGS
#pragma comment(linker, "/stack:16777216")
#include <string>
#include <vector>
#include <map>
#include <list>
#include <iterator>
#include <set>
#include <queue>
#include <iostream>
#include <sstream>
#include <stack>
#include <deque>
#include <cmath>
#include <memory.h>
#include <cstdlib>
#include <cstdio>
#include <cctype>
#include <algorithm>
#include <utility> 
using namespace std;
 
#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define RFOR(i, b, a) for(int i = (b) - 1; i >= (a); --i)
#define REP(i, N) FOR(i, 0, N)
#define RREP(i, N) RFOR(i, N, 0)
#define FILL(A,value) memset(A,value,sizeof(A))
 
#define ALL(V) V.begin(), V.end()
#define SZ(V) (int)V.size()
#define PB push_back
#define MP make_pair
#define Pi 3.14159265358979
 
typedef long long Int;
typedef unsigned long long UINT;
typedef vector <int> VI;
typedef pair <int, int> PII;
 
const int INF = 2000000000;
const int MAX = 20000;
const int MAX2 = 1007;
const int BASE = 1000000000;
 
const int MOD = 1000000007;
 
struct test
{
	int n;
	VI U;
	VI V;
	test(){}
	void Write()
	{
		cout << n << endl;
		FOR (i,0,n-1)
		{
			cout << U[i]+1 << ' ' << V[i]+1 << endl;
		}
	}
	void Read()
	{
		cin >> n;
		FOR (i,0,n-1)
		{
			int u, v;
			cin >> u >> v;
			U.PB(u-1);
			V.PB(v-1);
		}
	}
	VI G[MAX];
	vector <PII> A;
	void dfs(int v, int p, int h)
	{
		A.PB(MP(h, v));
		FOR (i,0,SZ(G[v]))
		{
			int to = G[v][i];
			if (to == p)
				continue;
			dfs(to, v, h+1);
		}
	}
	void Solve()
	{
		FOR (i,0,n-1)
		{
			G[V[i]].PB(U[i]);
			G[U[i]].PB(V[i]);
		}
		A.clear();
		dfs(0, -1, 0);
		sort(ALL(A));
		int level = 0, l = 0, r = SZ(A)-1, cnt = 0;
		while (l <= r)
		{
			if (cnt % 2 == 0)
			{
				while (l < SZ(A) && A[l].first == level)
					++ l;
				++ level;
			}
			else
			{
				-- r;
			}
			++ cnt;
		}
		cout << cnt << endl;
	}
};
 
test Get1(int n)
{
	test res;
	res.n = n;
	vector <PII> E;
	VI P;
	FOR (i,0,n)
		P.PB(i);
	random_shuffle(P.begin()+1, P.end());
	FOR (i,1,n)
	{
		int v = rand() % i;
		E.PB(MP(P[v], P[i]));
	}
	FOR (i,0,SZ(E))
		if (rand() % 2)
			swap(E[i].first, E[i].second);
	random_shuffle(ALL(E));
	FOR (i,0,SZ(E))
	{
		res.U.PB(E[i].first);
		res.V.PB(E[i].second);
	}
	return res;
}
 
test Get2(int n, int m)
{
	test res;
	res.n = n;
	vector <PII> E;
	VI P;
	FOR (i,0,n)
		P.PB(i);
	random_shuffle(P.begin()+1, P.end());
	int val = rand() % m + 1;
	FOR (i,1,n)
	{
		int v = rand() % min(i, val);
		E.PB(MP(P[v], P[i]));
	}
	FOR (i,0,SZ(E))
		if (rand() % 2)
			swap(E[i].first, E[i].second);
	random_shuffle(ALL(E));
	FOR (i,0,SZ(E))
	{
		res.U.PB(E[i].first);
		res.V.PB(E[i].second);
	}
	return res;
}
 
test Get3(int n, int m)
{
	test res;
	res.n = n;
	vector <PII> E;
	VI P;
	FOR (i,0,n)
		P.PB(i);
	random_shuffle(P.begin()+1, P.end());
	int val = rand() % m + 1;
	FOR (i,1,n)
	{
		int v = max(0, i - rand() % val - 1);
		E.PB(MP(P[v], P[i]));
	}
	FOR (i,0,SZ(E))
		if (rand() % 2)
			swap(E[i].first, E[i].second);
	random_shuffle(ALL(E));
	FOR (i,0,SZ(E))
	{
		res.U.PB(E[i].first);
		res.V.PB(E[i].second);
	}
	return res;
}
 
void OpenInput(int cnt)
{
	char buf[256];
	sprintf(buf, "D:\\witua\\Cook-off August\\TREEGAME\\%d.in", cnt);
	freopen(buf, "wb", stdout);
}
 
void OpenOutput(int cnt)
{
	char buf[256];
	sprintf(buf, "D:\\witua\\Cook-off August\\TREEGAME\\%d.out", cnt);
	freopen(buf, "wb", stdout);
}
 
void WriteInput(vector <test> A)
{
	cout << SZ(A) << endl;
	FOR (i,0,SZ(A))
	{
		A[i].Write();
	}
}
 
void WriteOutput(vector <test> A)
{
	FOR (i,0,SZ(A))
		A[i].Solve();
}
 
void Do(vector<test> A, int cnt)
{
	OpenInput(cnt);
	WriteInput(A);
	OpenOutput(cnt);
	WriteOutput(A);
}
 
int main()
{
	int cnt;
	cin >> cnt;
	FOR (i,0,cnt)
	{
		test t;
		t.Read();
		t.Solve();
	}
	/*int cnt = 0;
	vector <test> A;
 
	A.clear();
	FOR (i,0,10)
		A.PB(Get1(100));
	Do(A, cnt ++);
 
	A.clear();
	FOR (i,0,10)
		A.PB(Get1(1000));
	Do(A, cnt ++);
 
	A.clear();
	FOR (i,0,3)
		A.PB(Get2(1000, 100));
	FOR (i,0,3)
		A.PB(Get2(1000, 10));
	FOR (i,0,3)
		A.PB(Get2(1000, 5));
	FOR (i,0,1)
		A.PB(Get2(1000, 1));
	Do(A, cnt ++);
 
	A.clear();
	FOR (i,0,3)
		A.PB(Get3(1000, 100));
	FOR (i,0,3)
		A.PB(Get3(1000, 10));
	FOR (i,0,3)
		A.PB(Get3(1000, 5));
	FOR (i,0,1)
		A.PB(Get3(1000, 1));
	Do(A, cnt ++);*/
	return 0;
}