#include <bits/stdc++.h>
#define nikah ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define ll long long
#define pll pair<ll,ll>
#define pb push_back
#define pp pop_back
#define fi first
#define se second
const ll maxn = 5e5+7, modn = 1e9+7;
using namespace std;
ll n,m,cur,tim;
vector<pll>adj[maxn];
bool cekedge[maxn], ceknode[maxn];
stack<ll>s;
void dfs(ll node) {
if (ceknode[node]) {
while (!s.empty()) {
ll x = s.top();
ceknode[x] = 0;
if (x == node) {
cout<<x<<endl;
break;
} else {
cout<<x<<" ";
}
s.pop();
}
} else {
s.push(node);
}
ceknode[node] = 1;
while (!adj[node].empty() && cekedge[adj[node].back().se]) adj[node].pp();
if (adj[node].empty()) return;
ll next = adj[node].back().fi, idx = adj[node].back().se;
cekedge[idx] = 1;
adj[node].pp();
dfs(next);
}
int main () {
nikah
cin>>n>>m;
for (ll i=1; i<=m; i++) {
ll u,v; cin>>u>>v;
adj[u].pb({v,i});
adj[v].pb({u,i});
}
for (ll i=1; i<=n; i++) {
if (!adj[i].empty()) dfs(i);
}
}
