n=input()
x=[]
y=[]
c=0
d=0

for i in range(n):
    a,b=raw_input().split(' ')
    x.append(int(a))
    y.append(int(b))

i=1

for i in range(1,n):
    if x[0]!=x[i]:
        c+=1
    if y[0]!=y[i]:
        d+=1
    i+=1

if c==0 or d==0:
    print 'YES'
else:
    print 'NO'