import sys

n = int(raw_input().strip())

a= []
for i in xrange(n):
    inp = map(int,raw_input().strip().split(' '))
    a.append(inp)

verticalpoint = a[0][0]
horizontalpoint = a[0][1]

bVertical = True
bHorizontal = True

for i in a:
    if i[0] != verticalpoint:
        bVertical = False
        break

for i in a:
    if i[1] != horizontalpoint:
        bHorizontal = False
        break

if bVertical or bHorizontal:
    print "YES"
else:
    print "NO"