#yuki274

n,m=map(int,raw_input().split())
a=[0 for i in xrange(m)]
for i in xrange(n):
 l,r=map(int,raw_input().split())
 for j in xrange(l,r+1):
  a[j]+=1
  a[m-j-1]+=1
if max(a)<=2:
 print 'YES'
else:
 print 'NO'