111540

#-*-coding:utf8;-*-
#qpy:3
#qpy:console

def dfs(g, i, c, s, used):
  used[i] = True
  s.append(i)
  c[len(c)-1]+= 1
  for j in g[i]:
    if not used[j]:
      dfs(g, j, c, s, used)


def csearch(g, n):
  count = 0
  used = [False for i in range(n+1)]
  c = []
  s = []
  for i in range(n):
    if not used[i+1]:
      count+= 1
      c.append(0)
      s.append([])
      dfs(g, i+1, c, s[len(s)-1], used)
  print(count)
  for i in range(count):
    print(c[i])
    for j in s[i]:
      print(str(j) + " ", end = "")
    print()

#*****************

n, m = map(int, input().split())
g = [[] for i in range(n+1)]
for i in range(m):
  a, b = map(int, input().split())
  g[a].append(b)
  g[b].append(a)

#for i in g: print(i)

csearch(g, n)