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
    elif j in ans:
        continue
    else:
        ans.append(j)
for k in ans:
    print(k)