# your code goes here
t=input()
c=[]
d=[]
for i in range(t):
	n,m=map(int,raw_input().split())
	c.append(n)
	d.append(m)
for i in range(t):
	p=max(c)
	q=min(c)
	a=max(d)
	b=min(d)
if(p==q):
	print 'YES'
elif(a==b):
	print 'YES'
else:
	print 'NO'