#include<bits/stdc++.h>
using namespace std;
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define int long long
#define endl '\n'
#define N 100000
#define pi acos(-1)
#define tora acos(-1)/180
#define tode 180/acos(-1)
#define pque priority_queue
typedef pair < int, int > ii;
typedef vector < int > vi;
typedef vector < vi > vii;
int mod = 1000000007 ;
int check[500009], edge[500009], n, m, a, b;
vector<ii> v[500009];
stack<int> st;
void dfs(int u)
{
//cout << u << endl;
if(check[u] == 1)
{
while(!st.empty())
{
int id = st.top();
cout << id << ' ';
check[id] = 0;
st.pop();
if(id == u)
break;
}
cout << endl;
}
check[u] = 1;
st.push(u);
for(int i = 0; i < (int)v[u].size(); i++)
if(edge[v[u][i].se] == 0 && check[u] == 1)
{
edge[v[u][i].se] = 1;
dfs(v[u][i].fi);
}
}
signed main()
{
//ios_base::sync_with_stdio(0);
cin >> n >> m;
for(int i = 1; i <= m; i++)
{
cin >> a >> b;
v[a].pb(mp(b, i));
v[b].pb(mp(a, i));
}
for(int i = 1; i <= n; i++)
dfs(i);
}
