N=int(input())
name2=[]
for i in range(N):
    name2.extend(input().split())

name1=[]

for i in range(N):
    name1.append(name2[i])
    del name2[i]

ans=[]
for j in name2:
    if j in name1:
        continue
    else:
        ans.append(j)
    
kk=[]
for k in ans:
    if k in kk:
        continue
    else:
        print(k)
        kk.append(k)