# coding: utf-8
# Your code here!
N=int(input())
org=[]
dic={}
for _ in range(N):
    A,B=input().split()
    org.append(B)
    if A in dic:
        dic[A][0]+=1
    else:
        dic[A]=[1,0]
    
    if B in dic:
        dic[B][1]+=1
    else:
        dic[B]=[0,1]

for k in dic:
    if dic[k][0]==0:
        print(k)