n = int(input())
s, t = [], []
for _ in range(n):
    s_, t_ = input().split()
    s.append(s_)
    t.append(t_)
for i in range(n):
    sflag = True
    for j in range(n):
        if i == j:
            continue
        if s[i] == s[j] or s[i] == t[j]:
            sflag = False
            break
    tflag = True
    for j in range(n):
        if i == j:
            continue
        if t[i] == s[j] or t[i] == t[j]:
            tflag = False
            break
    if sflag == False and tflag == False:
        print("No")
        break
else:
    print("Yes")