Connected components

from collections import defaultdict

n, m = map(int, input().split())
g = defaultdict(list)
for _ in range(m):
    a, b = map(int, input().split())
    g[a].append(b)
    g[b].append(a)

comps = []
visited = set()


def dfs(node):
    if node not in visited:
        visited.add(node)
        comps[-1].append(node)
        for neigh in g[node]:
            dfs(neigh)

for v in range(1, n+1):
    if v not in visited:
        comps.append([])
        dfs(v)

print(len(comps))
for c in comps:
    print(len(c))
    print(' '.join([str(i) for i in c]))