l=[]
cnt=0
n=int(input())
for i in range(n):
    q=list(map(int,input().split()))
    if q[0]==0:
        continue
    l.append(q[1:])

cnt=0
ans=[]
while l:
    for x in l:
        if len(x)==0:
            continue
        ans.append(x.pop(0))


print(ans)