/**
* author: wxhtzdy
* created: 01.05.2023 14:41:43
**/
#include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int n, m;
cin >> n >> m;
vector<int> u(m), v(m);
vector<vector<int>> g(n);
for (int i = 0; i < m; i++) {
cin >> u[i] >> v[i];
--u[i]; --v[i];
g[u[i]].push_back(i);
g[v[i]].push_back(i);
}
vector<bool> rem(m);
vector<bool> was(n);
vector<int> ptr(n);
vector<int> stk;
function<void(int)> Dfs = [&](int x) {
if (was[x]) {
while (stk.size()) {
int ver = stk.back();
stk.pop_back();
cout << ver + 1 << " ";
was[ver] = false;
if (ver == x) {
break;
}
}
cout << '\n';
return;
}
stk.push_back(x);
was[x] = true;
for (; ptr[x] < (int) g[x].size(); ptr[x]++) {
int e = g[x][ptr[x]];
if (rem[e]) {
continue;
}
int y = (x ^ u[e] ^ v[e]);
rem[e] = true;
Dfs(y);
ptr[x]++;
return;
}
stk.pop_back();
was[x] = false;
};
for (int i = 0; i < n; i++) {
Dfs(i);
}
return 0;
}
