#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;
vi labels;
int dfs_timer = 0;
vi adj[mxN];

void dfs(int s, int p){
	labels[s] = dfs_timer++;
	for(auto u : adj[s])
		if(u!=p) dfs(u,s);
	labels[s]*=1000; labels[s]+=dfs_timer;
}

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);
	for(int i = 0; i < n; i++){
		int stS = i/1000, enS = i%1000;
		cout << stS << " " << enS << "\n";
	}
	return labels;
}

int isAnc(int s, int t){
	int stS = s/1000, enS = s%1000;
	int stT = t/1000, enT = t%1000;
	return stS<=stT and enS>=enT;
}

int find_next_station(int s, int t, vi c) {
	for(auto u : c) if(u==t) return u;
	int par;
	for(int i = 0; i < sz(c); i++){
		if(isAnc(c[i],s)){
			par=c[i]; continue;
		}
		if(isAnc(c[i],t)) return c[i];
	}
	return par;/*
	if(t < s) return c[0];
	int pos = lower_bound(all(c),t+1)-begin(c)-1;
	if(pos!=-1 and pos<sz(c)-1) return c[pos];
	if() return c[0];
	return c.back();*/
}