n=int(input())
k1=[]
k2=[]
ras=[]
sp=[]
s=0
l=0
while s<n:
    sp.append(list(input().split()))
    s+=1
s=0
k1.append(1)
while s<n:
    l=0
    while l<len(sp[s])-1:
        if (s+1)<int(sp[s][l]):
            if ((s+1) not in k1) and ((s+1) not in k2):
                k1.append(s+1)
            if (s+1) in k1:
                if int(sp[s][l]) not in k1:
                    k2.append(int(sp[s][l]))
            elif int(sp[s][l]) not in k2:
                k1.append(int(sp[s][l]))
        l+=1
    s+=1
print(len(k1))
s=0
stok=''
while s<len(k1):
    stok=stok+str(k1[s])+' '
    s+=1
print(stok)