user01 = int(input())
i = 0
dict_word = {}
while True:
    if user01 <= i:
        break
    user02 = input().split(" ")
    dict_word[user02[0]] = user02[1]
    i+=1

user03 = input()
flag = True
for key, val in dict_word.items():
    if val == user03:
        flag = False
        print(key)
    if key == user03:
        flag = False
        print(val)

if flag:
    print("No synonim")