n = int(input())
a = list()
k = 0

for j in range(n):
    b = list()
    lst = list(map(int, input().split()))
    lst.reverse()
    p = lst.pop()
    k = max(k, p)
    while lst != list():
        b.append(lst.pop())
    a.append(b)

ans = list()
for i in range(k):
    for j in range(n):
        if i < len(a[j]): ans.append(a[j][i])

print(*ans)