n=int(input())
que=[]
found=set()
removed=set()
for i in range(n):
    a,b=input().split()
    if a not in found:
        que.append(a)
        found.add(a)
    if b not in found:
        que.append(b)
        found.add(b)
    removed.add(a)
for b in que:
    if b not in removed:
        print(b)