新学的$Python$

结果全部 $RE$

n,m,t=map(int,input().split())
b=[0 for i in range(1000005)]
c=[0 for i in range(1000005)]
ans=0
for i in range(n):
    s=input()
    p=s.find(" ")
    k=int(s[:p])
    s=s[p+1:]
    a=list(map(int,s.split()))
    for j in range(k):
        b[a[j]]+=1
for i in range(1,m+1):
    if b[i]==t:
        c[ans]=i
        ans+=1
print(ans)
for i in range(ans):print(c[i],end=" ")