N = int(input())
M = {}
name_list = []

for _ in range(N):
    a,b = map(str,input().split())
    M.setdefault(a,0)
    M.setdefault(b,0)
    if a not in name_list:
        name_list.append(a)
    if b not in name_list:
        name_list.append(b)
    M[a] += 1
for n in name_list:
    if M[n] == 0:
        print(n)