#include <queue>

 #include <cstdio>

 #include <cstring>

 #include <iostream>

 #define N 20001

 #define min(x, y) ((x) < (y) ? (x) : (y))

 #define max(x, y) ((x) > (y) ? (x) : (y))

 int n, m, cnt, sum, s, t;

 int head[N], belong[N], to[N], next[N], val[N], suc[N], cur[N], dis[N];

 inline int read()

 {

     int x = , f = ;

     char ch = getchar();

     for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = -;

     for(; isdigit(ch); ch = getchar()) x = (x << ) + (x << ) + ch - '';

     return x * f;

 }

 inline void add(int x, int y, int z)

 {

     to[cnt] = y;

     val[cnt] = z;

     next[cnt] = head[x];

     head[x] = cnt++;

 }

 inline bool bfs()

 {

     int i, u, v;

     std::queue <int> q;

     memset(dis, -, sizeof(dis));

     q.push(s);

     dis[s] = ;

     while(!q.empty())

     {

         u = q.front(), q.pop();

         for(i = head[u]; i ^ -; i = next[i])

         {

             v = to[i];

             if(val[i] && dis[v] == -)

             {

                 dis[v] = dis[u] + ;

                 if(v == t) return ;

                 q.push(v);

             }

         }

     }

     return ;

 }

 inline int dfs(int u, int maxflow)

 {

     if(u == t) return maxflow;

     int i, v, d, ret = ;

     for(i = cur[u]; i ^ -; i = next[i])

     {

         v = to[i];

         if(val[i] && dis[v] == dis[u] + )

         {

             d = dfs(v, min(val[i], maxflow - ret));

             ret += d;

             cur[u] = i;

             val[i] -= d;

             val[i ^ ] += d;

             if(d) suc[u] = v - n;

             if(ret == maxflow) return ret;

         }

     }

     return ret;

 }

 int main()

 {

     int i, j, x, y, now;

     n = read();

     m = read();

     s = , t = (n << ) + ;

     memset(head, -, sizeof(head));

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

     {

         x = read();

         y = read();

         add(x, y + n, );

         add(y + n, x, );

     }

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

     {

         add(s, i, );

         add(i, s, );

         add(i + n, t, );

         add(t, i + n, );

     }

     while(bfs())

     {

         for(i = s; i <= t; i++) cur[i] = head[i];

         sum += dfs(s, 1e9);

     }

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

         if(suc[i])

         {

             now = i;

             while(now)

             {

                 printf("%d ", now);

                 x = suc[now];

                 suc[now] = ;

                 now = x;

             }

             puts("");

         }

     printf("%d\n", n - sum);

     return ;

 }