//#pragma GCC target("avx2")
//#pragma GCC optimize("O3")
//# include <x86intrin.h>
#include "meetings.h"
# include <bits/stdc++.h>
# include <ext/pb_ds/assoc_container.hpp>
# include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
template<typename T> using ordered_set = tree <T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define _USE_MATH_DEFINES_
#define ll long long
#define ld long double
#define Accepted 0
#define pb push_back
#define mp make_pair
#define sz(x) (int)(x.size())
#define every(x) x.begin(),x.end()
#define F first
#define S second
#define lb lower_bound
#define ub upper_bound
#define For(i,x,y) for (ll i = x; i <= y; i ++)
#define FOr(i,x,y) for (ll i = x; i >= y; i --)
#define SpeedForce ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)
// ROAD to... Red
inline void Input_Output () {
//freopen(".in", "r", stdin);
//freopen(".out", "w", stdout);
}
const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, -1, 0, 1};
int n, m, k;
vector < int > g[2020];
int e[2020][2020];
int deg[2020];
int u[2020];
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
void Bridge (int, int);
int Query (int, int, int);
int opera = 0;
map < pair < int, int > , int > was;
void PrintOut(int a, int b) {
if (a > b) swap(a, b);
opera++;
if (opera == n) {
assert(0);
}
// cerr << ' ' << a << ' ' << b << ' ' << opera << '\n';
// if (opera == 1) exit(0);
Bridge(a, b);
}
void reduce (vector < int > &v) {
sort(every(v));
v.resize(unique(every(v)) - v.begin());
random_shuffle(every(v));
}
void go (int v) {
if (g[v].empty()) return;
// reduce(g[v]);
vector < int > cur;
cur.swap(g[v]);
int len = cur.size();
int y = cur[rng() % len];
int x = v;
set < int > s;
s.insert(v);
s.insert(y);
for (int z : cur) if (z != y) {
// cout << x << ' ' << y << ' ' << z << '\n';
int t = Query(x, y, z);
s.insert(t);
if (t != z) g[t].pb(z);
}
//exit(0);
vector < int > ord(s.begin(), s.end());
// for (auto it : ord) cout << it << ' ';
// exit(0);
sort(every(ord), [&](int y, int z) {
return (x == y) || ((x != z) && Query(x, y, z) == y);
} );
// cout << sz(ord);
// exit(0);
for (int i = 1; i < sz(ord); ++i) {
PrintOut(ord[i-1], ord[i]);
}
for (auto it : ord)
go(it);
}
void Solve(int N) {
n = N;
opera = 0;
for (int i = 1; i < n; ++i)
g[0].pb(i);
go(0);
}
/*
namespace {
const int MAX_N = 2000;
const int MAX_CALLS = 100000;
void WrongAnswer(int code) {
printf("Wrong Answer [%d]\n", code);
exit(0);
}
int N, num_calls;
std::vector<int> graph[MAX_N];
std::set<std::pair<int, int>> edges, edges_reported;
int weight[MAX_N];
bool Visit(int p, int e, int rt = -1) {
if (p == e) {
++weight[p];
return true;
}
for (int q : graph[p]) {
if (q != rt) {
if (Visit(q, e, p)) {
++weight[p];
return true;
}
}
}
return false;
}
} // namespace
int Query(int u, int v, int w) {
if (!(0 <= u && u <= N - 1 && 0 <= v && v <= N - 1 && 0 <= w && w <= N - 1 &&
u != v && u != w && v != w)) {
WrongAnswer(1);
}
if (++num_calls > MAX_CALLS) {
WrongAnswer(2);
}
std::fill(weight, weight + N, 0);
Visit(u, v);
Visit(u, w);
Visit(v, w);
for (int x = 0; x < N; ++x) {
if (weight[x] == 3) {
return x;
}
}
printf("Error: the input may be invalid\n");
exit(0);
}
void Bridge(int u, int v) {
if (!(0 <= u && u < v && v <= N - 1)) {
WrongAnswer(3);
}
if (!(edges.count(std::make_pair(u, v)) >= 1)) {
WrongAnswer(4);
}
if (!(edges_reported.count(std::make_pair(u, v)) == 0)) {
WrongAnswer(5);
}
edges_reported.insert(std::make_pair(u, v));
}
int main() {
if (scanf("%d", &N) != 1) {
fprintf(stderr, "Error while reading input\n");
exit(1);
}
for (int i = 0; i < N - 1; ++i) {
int u, v;
if (scanf("%d%d", &u, &v) != 2) {
fprintf(stderr, "Error while reading input\n");
exit(1);
}
graph[u].push_back(v);
graph[v].push_back(u);
edges.insert(std::make_pair(u, v));
}
num_calls = 0;
Solve(N);
if (edges_reported.size() != static_cast<size_t>(N - 1)) {
WrongAnswer(6);
}
printf("Accepted: %d\n", num_calls);
return 0;
}
// B...a */
