n,h=map(int,input().split())
ab=[[*map(int,input().split())]for _ in range(n)]
d=[0]*(h+1)
for a,b in ab:
  d[a]+=1
  d[b+1]-=1
s=ans=0
for i in range(h+1):
  s+=d[i]
  ans=max(ans,s)
print(ans)