C-masala

n,h=map(int,input().split())
s=[0]*(h+5)
for i in range(n):
   a,b=map(int,input().split())
   s[a]+=1
   s[b+1]-=1
for i in range(1,len(s)):
   s[i]+=s[i-1]
print(max(s))