import sys
from itertools import count


def input(): return sys.stdin.readline().rstrip('\n')


def main():
    n = int(input())
    arr = [input().split()[:0:-1] for _ in range(n)]

    ans = []
    while any(arr):
        for v in arr:
            if v:
                ans.append(v.pop())

    print(*ans)


if __name__ == '__main__':
    main()