program ctc;
var f,g:text;
    n,m,i,j,nr,x,y,c,c2:longint;
    a,b:array of array of longint;
    viz,viz1:array of 0..1;
    retin:array  of longint;

procedure dfs(i:longint);
var j:longint;
begin
 viz[i]:=1;
 for j:=1 to a[i,0] do
  if viz[a[i,j]]=0 then
   dfs(a[i,j]);
  nr:=nr+1;
  retin[nr]:=i;
end;

procedure dfst (i:longint);
var j:longint;
begin
 viz1[i]:=1;
 c2:=c2+1;
 setlength (a[c],c2+1);
 a[c,c2]:=i;

 for j:=1 to b[i,0] do
  if viz1[b[i,j]]=0 then
  begin
   dfst(b[i,j]);
  end;
end;

begin
 assign (f,'ctc.in'); reset (f);
 assign (g,'ctc.out'); rewrite (g);
 readln (f,n,m);
 setlength (a,n+1,1);
 setlength (b,n+1,1);
 for i:=1 to m do
 begin
  readln (f,x,y);
  setlength (a[x],length (a[x])+1);
  a[x,0]:=a[x,0]+1;
  a[x,a[x,0]]:=y;
  setlength (b[y],length (b[y])+1);
  b[y,0]:=b[y,0]+1;
  b[y,b[y,0]]:=x;
 end;
 setlength (viz,n+1);
 setlength (retin,n+1);
 nr:=0;
 for i:=1 to n do
  if viz[i]=0 then
   dfs(i);
 c:=0;
 setlengtH (viz1,n+1);
 for i:=nr downto 1 do
  if viz1[retin[i]]=0 then
  begin
  c:=c+1; c2:=0;
  setlength (a[c],1);
   dfst(retin[i]);
   a[c,0]:=c2;
  end;
  writeln (g,c);
  for i:=1 to c do
  begin
   for j:=1 to a[i,0] do
    write (g,a[i,j], ' ');
   writeln (G);
  end;
 close (F); close (g);
end.