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

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