#include "islands.h"
#include <bits/stdc++.h>
using namespace std;
const int M = 1000;
vector<int> nei[M],ans;
map<pair<int,int>,int> ind;
int vis[M], par[M];
void dfs(int u)
{
vis[u]=1;
if (ans.size()) return;
for (int i:nei[u])
{
if (!vis[i])
par[i]=u,dfs(i);
else if(vis[i]==1)
{
int v=u;
while (v)
ans.push_back(ind[{par[v],v}]),v=par[v];
reverse(ans.begin(),ans.end());
ans.push_back(ind[{u,i}]);
v=u;
vector<int> c;
while (v!=i)
c.push_back(ind[{par[v],v}]),v=par[v];
reverse(c.begin(),c.end());
c.push_back(ind[{u,i}]);
for (int x:c)
ans.push_back(x+1);
reverse(c.begin(),c.end());
for (int x:c)
ans.push_back(x);
for (int x:c)
ans.push_back(x+1);
v=i;
while (v)
ans.push_back(ind[{par[v],v}]),v=par[v];
}
if (ans.size()) return;
}
vis[u]=2;
}
variant<bool, vector<int>> find_journey(int n, int m, vector<int> U, vector<int> V)
{
for (int i=0;i<m;i+=2)
nei[U[i]].push_back(V[i]),ind[{U[i],V[i]}]=i;
dfs(0);
if (ans.size()) return ans;
return false;
}
