from collections import defaultdict



beenThere = []

n, m = list(map(int, input().split()))
graf = defaultdict(list)

kiElerheto = set()
kiSzamlalo = 0


#todo Is there a way without array?
arr = [0 for i in range(n)]

for i in range(m):
    honnan1, hova = list(map(int, input().split()))

    graf[honnan1].append(hova)
    graf[hova].append(honnan1)

    arr[honnan1-1] += 1
    arr[hova-1] += 1

zsakfalvak = []
zsakfalvak = [i+1 for i, value in enumerate(arr) if value == 1]

for i in zsakfalvak:
    l = graf[i][0]
    kiElerheto.add(l)
    while len(graf[l]) <= 2:
        if graf[l][0] != i:
            kiElerheto.add(graf[l][0])
            l = graf[l][0]
            i = l
        else:
            kiElerheto.add(graf[l][1])
            l = graf[l][1]
            i = l


print(len(kiElerheto))
print(*sorted(kiElerheto))