students = {}
num = int(input())

for k in num:
    line = input().split()

    cheater = line[0]
    writer = line[1]

    if not cheater in students:
        students[cheater] = True
    else:
        students[cheater] = True

    if not writer in students:
        students[writer] = False

for key, value in  students.iteritems():
    if value:
        print(key)