#include<iostream> #include<cstring> #include<cstdio> #define inf 0x7fffffff using namespace std; inline int read(){ int x=0,f=1;char ch=getchar(); while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();} while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();} return x*f; } struct edge{ int to,next,v; }e[500001]; int n,m,cnt=1,ans,T=8001,head[50001],h[50001],to[50001]; bool mark[50001]; void ins(int u,int v,int w){ e[++cnt]=(edge){v,head[u],w};head[u]=cnt; e[++cnt]=(edge){u,head[v],0};head[v]=cnt; } inline bool bfs(){ int q[50001],t=0,w=0; memset(h,-1,sizeof(h)); h[0]=0;q[0]=0; while(t<=w){ int now=q[t++]; for(int i=head[now];i;i=e[i].next) if(e[i].v&&h[e[i].to]==-1) h[e[i].to]=h[now]+1,q[++w]=e[i].to; } if(h[T]==-1)return 0; else return 1; } inline int dfs(int x,int f){ if(x==T)return f; int rest,used=0; for(int i=head[x];i;i=e[i].next){ if(e[i].v&&h[e[i].to]==h[x]+1){ rest=f-used; rest=dfs(e[i].to,min(e[i].v,rest)); if(rest){ to[x]=e[i].to; if(e[i].to>n)mark[e[i].to-n]=1; } used+=rest; e[i].v-=rest; e[i^1].v+=rest; if(used==f)return f; } } if(!used)h[x]=-1; return used; } int main(){ freopen("path3.in","r",stdin); freopen("path3.out","w",stdout); n=read();m=read(); int a,b; for(int i=1;i<=m;i++){ a=read();b=read(); ins(a,b+n,inf); } for(int i=1;i<=n;i++)ins(0,i,1),ins(i+n,T,1); while(bfs())ans+=dfs(0,inf); for(int i=1;i<=n;i++){ if(mark[i])continue; printf("%d",i); int j=i; while(to[j]){ printf(" %d",to[j]-n); j=to[j]-n; } printf("\n"); } printf("%d\n",n-ans); return 0; }