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

for _ in range(N):
    a,b = map(str,input().split())
    c = {a:0}
    M.update(c)
    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 n not in M:
        print(n)