N, H = map(int, input().split())

p = [0 for _ in range(H+1)]

for i in range(N):
	a, b = map(int, input().split())
	p[a] += 1
	p[b+1] -= 1

pp = [p[0]]
for i in range(1, H+1):
	pp.append(pp[-1]+p[i])

print(max(pp))