N, H = map(int, input().split())
imos = [0 for _ in range(H+2)]

for _ in range(N):
	A, B = map(int, input().split())
	imos[A] += 1
	imos[B+1] -= 1

for i in range(N):
	imos[i+1] += imos[i]

print(max(imos))