n, m = list(map(int, input().split()))
graph = [[] for _ in range(n)]
for _ in range(m):
    a, b = list(map(int, input().split()))
    graph[a-1].append(b-1)
    graph[b-1].append(a-1)  # 有向グラフなら消す
print(graph)  # [[2, 3, 5], ..., [1, 3, 4]]