#include <bits/stdc++.h>

using namespace std;

#define ls(p) p << 1

#define rs(p) p << 1 | 1

const int M = 1e5 + ;

int n, m, cnt;

int rt[M];

struct node{

    int fa, ch[], val, cnt, sz, lazy;

}spl[M];

bool ident(int x, int f) {

    return spl[f].ch[] == x;

}

void connect(int x, int f, int s){

    spl[f].ch[s] = x;

    spl[x].fa = f;

}

void update(int now) {

    spl[now].sz = spl[spl[now].ch[]].sz + spl[spl[now].ch[]].sz + spl[now].cnt;

}

void push_down(int now) {

    if(!spl[now].lazy) return;

    swap(spl[now].ch[], spl[now].ch[]);

    spl[spl[now].ch[]].lazy ^= ;

    spl[spl[now].ch[]].lazy ^= ;

    spl[now].lazy = ;

}

void rotate(int x) {

    int f = spl[x].fa, ff = spl[f].fa, k = ident(x, f);

    connect(spl[x].ch[k ^ ], f, k);

    connect(x, ff, ident(f, ff));

    connect(f, x, k ^ );

    update(f), update(x);

}

void splaying(int p, int x, int top) {

    if(!top) rt[p] = x;

    //printf("top = %d\n", top);

    while(spl[x].fa != top) {

        //if(num <= 5) num++, printf("\n%d %d\n", x, top);

        int f = spl[x].fa, ff = spl[f].fa;

        if(ff != top) ident(f, ff) ^ ident(x, f) ? rotate(x) : rotate(f);

        rotate(x);

    }

}

int find_r(int now) {

    push_down(now);

    while(spl[now].ch[]) {

        now = spl[now].ch[];

        push_down(now);

    }

    return now;

}

int find_l(int now) {

    push_down(now);

    while(spl[now].ch[]) {

        now = spl[now].ch[];

        push_down(now);

    }

    return now;

}

void newnode(int now, int val) {

    spl[now].val = val;

    spl[now].sz = ;

    spl[now].cnt = ;

    spl[now].ch[] = ;

    spl[now].ch[] = ;

    spl[now].fa = ;

    spl[now].lazy = ;

}

void work(){

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

        rt[i] = i;

        newnode(i, i);

    }

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

        int u, v;

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

        if(!rt[u]) {

            if(rt[v]){

                rt[u] = rt[v];

                spl[rt[u]].lazy ^= ;

                rt[v] = ;

            }

        }

        else if(!rt[v]) {

            spl[rt[u]].lazy ^= ;

        }

        else {

            int r = find_r(rt[u]);

            splaying(u, r, );

            //printf("1 \n");

            int l = find_l(rt[v]);

            //printf("3\n");

            splaying(v, l, );

            //printf("2\n");

            connect(l, r, );

            spl[rt[u]].lazy ^= ;

            rt[v] = ;

            update(rt[u]);

        }

    }

}

void out(int now){

    if(!now) return;

    push_down(now);

    out(spl[now].ch[]);

    printf("%d ", spl[now].val);

    out(spl[now].ch[]);

}

int main(){

    while(~scanf("%d%d", &n, &m)){

        cnt = ;

        work();

        printf("%d ", spl[rt[]].sz);

        if(spl[rt[]].sz) out(rt[]);

        printf("\n");

    }

    return ;

}

/*

999 5

99 8

8 99

99 8

7 99

1 7

*/

/*

999 5

1 3

1 4

1 5

1 6

1 7

*/