n = int(input())

st = [input().split() for _ in range(n)]

dic = {}
for i in range(n):
    if st[i][0] not in dic:
        dic[st[i][0]] = 1
    else:
        dic[st[i][0]] += 1
    if st[i][1] not in dic:
        dic[st[i][1]] = 1
    else:
        dic[st[i][1]] += 1
        
flag = True
for s, t in st:
    if dic[s] == 1 or dic[t] == 1:
        flag = True
    else:
        flag = False
        break

print("Yes" if flag else "No")