N,H=(int(x) for x in input().split())
mem=[0]*H
for i in range(N):
	A,B=(int(x) for x in input().split())
	mem[A] += 1
	if B != len(mem)-1:
	  mem[B+1] -= 1
ans=[mem[0]]
for i in range(1,len(mem)):
	ans.append(ans[-1]+mem[i])
print(max(ans))