n = int(input())
s = set()
st = set()
l = []
for _ in range(n):
    a, b = input().split()
    l.append(b)
    s.add(a)
    s.add(b)
    st.add(a)
s = s - st
t = set()
for x in l:
    if x not in t:
        t.add(x)
        if x in s:
            print(x)