# include <stdio.h>

# include <string.h>

# include <algorithm>

// # include <bits/stdc++.h>

using namespace std;

typedef long long ll;

typedef long double ld;

typedef unsigned long long ull;

const int M =  + ;

const int mod = 1e9+;

# define RG register

# define ST static

int n, m;

int head[M], nxt[M], to[M], tot = ;

inline void add(int u, int v) {

    ++tot; nxt[tot] = head[u]; head[u] = tot; to[tot] = v;

}

inline void adde(int u, int v) {

    add(u, v);

    add(v, u);

}

bool vis[M];

int Final;

int c[M], cn, p[M];

inline void dfs(int x) {

    if(p[x] != -) {

        printf("%d", x);

        for (int i=p[x]+; i<=cn; ++i) {

            printf(" %d", c[i]);

            p[c[i]] = -;

        }

        puts("");

        cn = p[x];

        return;

    }

    c[++cn] = x;

    p[x] = cn;

    for (int i=head[x]; i; i=nxt[i]) {

        if(vis[i] || vis[i^]) continue;

        head[x] = nxt[i];

        vis[i] = ;

        dfs(to[i]);

        if(p[x] == -) break;

    }

}

int main() {

    scanf("%d%d", &n, &m);

    for (int i=; i<=m; ++i) {

        int u, v; scanf("%d%d", &u, &v);

        adde(u, v);

    }

    for (int i=; i<=n; ++i) p[i] = -;

    for (int i=; i<=tot; i++)

        if(!vis[i] && !vis[i^])

            dfs(to[i]); 

    return ;

}