#include <bits/stdc++.h>
using namespace std;
//#define int long long
#define pii pair<int, int>
variant<bool, vector<int>> n2(int n, int M, vector<int> U, vector<int> V) {
vector<int> u0, u1;
for (int i = 0; i < M; i++) {
if (U[i]) u1.push_back(i);
else u0.push_back(i);
}
if (u1.size() > 0 && u0.size() > 1) {
vector<int> ans = {u0[0], u1[0], u0[1], u0[0], u1[0], u0[1]};
return ans;
} else {
return false;
}
}
void dfs(int v, int p, vector<vector<pii>> &g, vector<bool> &uu, vector<int> &ps) {
if (uu[v]) return;
uu[v] = 1;
ps[v] = p;
for (auto [u, _] : g[v]) {
dfs(u, v, g, uu, ps);
}
}
variant<bool, vector<int>> undirected(int n, int M, vector<int> U, vector<int> V) {
vector<vector<pii>> g(n);
for (int i = 0; i < M; i++) {
g[U[i]].push_back({V[i], i});
}
if (g[0].size() > 1) {
int u = g[0][0].first, v = g[0][1].first;
if (u == v) {
vector<int> ans = {g[0][0].second, g[u][0].second, g[0][1].second,
g[0][0].second, g[u][0].second, g[0][1].second};
return true;
}
vector<int> ans = {g[0][0].second, g[u][0].second, g[0][1].second, g[v][0].second,
g[u][0].second, g[0][0].second, g[v][0].second, g[0][1].second};
return true;
}
vector<bool> uu(n);
vector<int> p(n);
dfs(0, 0, g, uu, p);
for (int i = 0; i < n; i++) {
if (g[i].size() > 2 && uu[i]) return true;
}
return false;
}
variant<bool, vector<int>> find_journey(int n, int M, vector<int> U, vector<int> V) {
if (n == 2) return n2(n, M, U, V);
return undirected(n, M, U, V);
}
#ifdef ONLINE_JUDGE
signed main() {
variant<bool, vector<int>> ans = find_journey(3, 4, {0, 1, 1, 0}, {1, 0, 0, 1});
cout << get<vector<int>>(ans).size() << "\n";
}
#endif
