from collections import defaultdict

N = int(input())
st = set()
st2 = set()
ls = []
k = 0

for i in range(N):
  s, t = input().split()
  if s not in st:
    st.add(s)
    ls.append(s)
  if t not in st:
    st.add(t)
    ls.append(t)
  st2.add(s)

for x in ls:
  if x not in st2:
    print(x)