n = int(raw_input())
xs = set()
ys = set()
for i in range(n):
    (x,y) = map(int,raw_input().split(' '))
    xs.add(x)
    ys.add(y)

if len(xs) == 1 or len(ys) == 1:
    print 'YES'
else:
    print 'NO'