//#include "insects.h"
#include<iostream>
#include<vector>
#include<queue>
#include<deque>
#include<string>
#include<fstream>
#include<algorithm>
#include <iomanip>
#include<map>
#include <set>
#include <unordered_map>
#include <stack>
#include <unordered_set>
#include <cmath>
#include <cstdint>
#include <cassert>
#include <bitset>
#include <random>
#include <chrono>
#include <cstring>
#include <variant>
#define shit short int
#define ll long long
#define ld long double
//#define int ll
#define For(i, n) for(int i = 0; i < (int)n; i++)
#define ffor(i, a, n) for(int i = (int)a; i < (int)n; i++)
#define rfor(i, n) for(int i = (int)n; i >= (int)0; i--)
#define rffor(i, a, n) for(int i = (int)n; i >= (int)a; i--)
#define vec vector
#define ff first
#define ss second
#define pb push_back
#define pii pair<long double, long double>
#define pld pair<ld, ld>
#define NEK 200000000000000
#define mod 1000000007
#define mod2 1000000009
#define rsz resize
#define prv 43
#define prv2 47
#define D 8
#define trav(a,x) for (auto& a: x)
#define pb push_back
#define ub upper_bound
#define lb lower_bound
#define all(x) (x).begin(), (x).end()
#define sig 0.0000001
using namespace std;
variant<bool, vector<int>> find_journey(int n, int m, vec<int> u, vec<int> v) {
vec<vec<pii>> g(n);
For(i, m) {
g[u[i]].push_back({ v[i], i });
}
vec<int> odp;
for (auto &i : g[0]) {
int ind = i.ss;
odp.push_back(ind);
if (ind % 2 == 0) {
odp.push_back(ind + 1);
}
else {
odp.push_back(ind - 1);
}
}
if (odp.size() == 0) {
return false;
}
return odp;
}
/*
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n, m; cin >> n >> m;
vec<int> u, v;
For(i, m) {
int a, b; cin >> a >> b;
u.push_back(a);
v.push_back(b);
}
variant<bool, vec<int>> odp = find_journey(n, m, u, v);
if (holds_alternative<bool>(odp)) {
cout << "odp is bool: " << get<bool>(odp) << endl;
}
else if (holds_alternative<vec<int>>(odp)) {
cout << "odp is vector: ";
for (int x : get<vec<int>>(odp)) {
cout << x << ' ';
}
cout << endl;
}
return 0;
}
*/
