#include "islands.h"
#include <bits/stdc++.h>
using namespace std;
#define sp " "
#define endl "\n"
#define pii pair<int, int>
#define st first
#define nd second
#define fileio() freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout)
#define fastio() cin.tie(0), ios_base::sync_with_stdio(0)
#define pb push_back
#define LL node * 2
#define RR node * 2 + 1
#define ll long long
#define MAXN 300005
const int modulo = 1e9 + 7;
const ll INF = 2e18 + 7;
vector<pii> in[MAXN], out[MAXN];
variant<bool, vector<int>> find_journey(int N, int M, vector<int> U, vector<int> V) {
for (int i = 0; i < M; i++){
in[V[i]].pb({U[i], i});
out[U[i]].pb({V[i], i});
}
if (out[0].size() >= 2 && in[0].size() >= 1){
int a = out[0][0].nd, b = out[0][1].nd, c = in[0][0].nd;
vector<int> v = {a, c, b, a, c, b};
return v;
}
return false;
}
/*
int main() {
fileio();
int N, M;
assert(2 == scanf("%d %d", &N, &M));
std::vector<int> U(M), V(M);
for (int i = 0; i < M; ++i) {
assert(2 == scanf("%d %d", &U[i], &V[i]));
}
std::variant<bool, std::vector<int>> result = find_journey(N, M, U, V);
if (result.index() == 0) {
printf("0\n");
if (std::get<bool>(result)) {
printf("1\n");
} else {
printf("0\n");
}
} else {
printf("1\n");
std::vector<int> &canoes = std::get<std::vector<int>>(result);
printf("%d\n", static_cast<int>(canoes.size()));
for (int i = 0; i < static_cast<int>(canoes.size()); ++i) {
if (i > 0) {
printf(" ");
}
printf("%d", canoes[i]);
}
printf("\n");
}
return 0;
}
*/
