n, h = map(int, input().split())
evs = []
for _ in range(n):
    a, b = map(int, input().split())
    evs.append((a, 1))
    evs.append((b + 1, -1))
now = ans = 0
for _, d in sorted(evs):
    now += d
    ans = max(ans, now)
print(ans)