class node:
    def __init__(self, name):
        self.color = 0
        self.neighbors = set()
        self.name = name
    def addEdge(self, other):
        self.neighbors.add(other)
        other.neighbors.add(self)
    def bfs(self):
        if self.color == 0:
            self.color = 1
            for n in self.neighbors:
                n.bfs()
    def unreachable(self):
        return self.color == 0

for _ in range(int(input())):
    names = {}
    main = None
    result = []
    for n in range(int(input())):
        name_list = input().split()
        anchor_name, name_list = name_list[0], name_list[1:]
        anchor = node(anchor_name)
        names[anchor_name] = anchor
        for name in name_list:
            if name in names:
                anchor.addEdge(names[name])
        if main == None:
            main = anchor
    main.bfs()
    for name in names:
        if names[name].unreachable():
            result.append(name)
    result.sort()
    for name in result:
        print(name, end=" ")
    print()