#include "stations.h"
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) begin(a),end(a)
using ll = long long;
using vi = vector<int>;
const int mxN = 1010;
int dfs_timer = 0;
vi labels, adj[mxN];

void dfs(int s, int p){
	for(auto u : adj[s])
		if(u!=p) dfs(u,s);
	labels[s] = dfs_timer++;
	cout << s << " " << labels[s] << "\n";
}

vi label(int n, int k, vi u, vi v) {
	labels.clear();
	labels.resize(n,0); dfs_timer=0;
	for(int i = 0; i < n; i++) adj[i].clear();
	for(int i = 0; i < sz(u); i++){
		int a = u[i], b = v[i];
		adj[a].pb(b), adj[b].pb(a);
	}
	dfs(0,-1);
	return labels;
}

int find_next_station(int s, int t, vi c) {
	if(sz(c)==1) return c[0];
	for(auto u : c) if(u==t) return u;
	if(t > s) return c.back();
	for(int i = 0; i < sz(c)-2; i++)
		if(c[i] < t and t < c[i+1]) return c[i+1];
	int sub0 = s-1-c[0];
	if(c[0]-sub0+1 <= t and t < c[0]) return c[0];
	return c.back();
}