from collections import defaultdict

N = int(input())
serial = defaultdict(int)
s1, s2 = set(), set()

for i in range(N):
    Ai, Bi = input().split()
    
    if Ai not in serial:
        serial[Ai] = i
    
    if Bi not in serial:
        serial[Bi] = i
        
    s1.add(Ai)
    s1.add(Bi)
    s2.add(Ai)
    
ans = []

for s1_i in s1:
    if s1_i not in s2:
        ans.append((s1_i, serial[s1_i]))

ans.sort(key=lambda k: k[1])

for ans_i, _ in ans:
    print(ans_i)