bfs

from queue import Queue
n, m = map(int, input().split())
g = [[] for i in range(n)]
for i in range(m):
    x, y = map(int, input().split())
    x -= 1
    y -= 1
    g[x].append(y)
    g[y].append(x)
used = [False] * n
q = Queue()
q.put(0)
used[0] = True
while not q.empty():
    cur = q.get()
    for nxt in g[cur]:
        if not used[nxt]:
            used[nxt] = True
            q.put(nxt)