#include <bits/stdc++.h>
#include <variant>
#include <vector>
using namespace std;
const int N=1e3+100;
int n,m;
vector<int> adj[N];
int color[N],parent[N];
map<pair<int,int>,int> helper;
int cycle_start, cycle_end;
bool dfs(int v) {
color[v] = 1;
for (int u : adj[v]) {
if(u==parent[v])continue;
if (color[u] == 0) {
parent[u] = v;
if (dfs(u))
return true;
} else if (color[u] == 1) {
if(u==0)
{
cycle_end = v;
cycle_start = u;
}
return true;
}
}
color[v] = 2;
return false;
}
vector<int> find_cycle() {
for(int i=0;i<n;i++)
{
color[i]=0;
parent[i]=-1;
}
cycle_start = -1;
for (int v = 0; v < n; v++) {
if (color[v] == 0 && dfs(v))
break;
}
if (cycle_start == -1) {
return {};
} else {
vector<int> cycle;
cycle.push_back(cycle_start);
for (int v = cycle_end; v!=cycle_start; v = parent[v])
cycle.push_back(v);
cycle.push_back(cycle_start);
reverse(cycle.begin(), cycle.end());
return cycle;
}
}
std::variant<bool, std::vector<int>> find_journey_1(int N, int M, std::vector<int> v1, std::vector<int> v2)
{
int n=N,m=M;
map<pair<int,int>,vector<int>> cnt;
for(int j=0;j<m;j++)
cnt[{v1[j],v2[j]}].push_back(j);
if(n>2)
{
for(int i=1;i<n;i++)
{
for(int j=i+1;j<n;j++)
{
if(cnt[{0,i}].size()==0 or cnt[{0,j}].size()==0 or cnt[{i,j}].size()==0)continue;
int edge01=cnt[{0,i}][0];
int edge10=cnt[{i,0}][0];
int edge02=cnt[{0,j}][0];
int edge20=cnt[{j,0}][0];
int edge12=cnt[{i,j}][0];
int edge21=cnt[{j,i}][0];
return vector<int>({edge01,edge12,edge20,edge02,edge21,edge10,edge20,edge12,edge01,edge10,edge21,edge02});
}
}
return false;
}
else if(cnt[{0,1}].size()>=2 and cnt[{1,0}].size()>=1)
{
int f=cnt[{0,1}][0];
int s=cnt[{0,1}][1];
int th=cnt[{1,0}][0];
return vector<int>({f,th,s,f,th,s});
}
else
{
return false;
}
}
std::variant<bool, std::vector<int>> find_journey(int N, int M, std::vector<int> v1, std::vector<int> v2)
{
n=N,m=M;
for(int j=0;j<m;j++)
{
helper[{v1[j],v2[j]}]=j;
adj[v1[j]].push_back(v2[j]);
}
vector<int> cur=find_cycle();
if(cur.size()==0)
{
return false;
}
else
{
vector<int> ed;
vector<int> oth;
for(int i=1;i<(cur.size());i++)
{
ed.push_back(helper[{cur[i-1],cur[i]}]);
int fp=ed.back();
oth.push_back(fp+((fp%2==0)?1:-1));
}
vector<int> ans;
for(auto i:ed)
{
ans.push_back(i);
}
reverse(begin(oth),end(oth));
for(auto i:oth)
{
ans.push_back(i);
}
reverse(begin(ed),end(ed));
for(auto i:ed){
ans.push_back(i);
}
reverse(begin(oth),end(oth));
for(auto i:oth)
{
ans.push_back(i);
}
return ans;
}
return false;
}
