from sys import setrecursionlimit
setrecursionlimit(10**5)

n, m = map(int, input().split())
graph = {}
for i in range(n):
    graph[i] = set()
for i in range(m):
    k, l = map(int, input().split())
    s1 = graph[k-1]
    s2 = graph[l-1]
    s1.add(l-1)
    s2.add(k-1)

colors = [0] * n
components = []
def dfs(u):
    global comp
    comp.append(u+1)
    colors[u] = 1
    s = graph[u]
    for i in s:
            if colors[i] != 1:
                dfs(i)

for i in range(n):
    if colors[i] == 1:
        continue
    comp = []
    dfs(i)
    components.append(comp)

print(len(components))
for i in range(len(components)):
    component = components[i]
    print(len(component))
    print(*component)