from sys import stdin

def main():
    N,M = [int(i) for i in input().split()]
    U = [[] for i in range(N+1)]
    for i in range(M):
        a,b = [int(i) for i in stdin.readline().split()]
        if b not in U[a]:
            U[a].append(b)
        if a not in U[b]:
            U[b].append(a)
    zs = [i for i in range(1,N+1) if len(U[i]) == 1]
    ent = []
    for zsak in zs:
        falu = U[zsak][0]
        if falu not in ent:
            ent.append(falu)
        elozo = zsak
        while len(U[falu]) == 2:
            if U[falu][0] == elozo:
                elozo,falu = U[falu]
            else:
                falu,elozo = U[falu]
            if falu not in ent:
                ent.append(falu)
        if falu not in ent:
            ent.append(falu)
    print(len(ent))
    if ent != []:
        ent.sort()
        print(*ent)
main()