from collections import Counter

N=int(input())

A=[input().split() for i in range(N)]

X=Counter()
Y=Counter()

for a,b in A:
    X[a]+=1
    Y[b]+=1

flag=1

for a,b in A:
    if X[a]>=2 and Y[b]>=2:
        flag=0

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