n, h = map(int, input().split())
events = []
max_r = 0

for _ in range(n):
    l, r = map(int, input().split())
    events.append((l, 1))
    events.append((r + 1, -1))
    max_r = max(max_r, r)

now, ans = 0, 0
for _, v in events:
    now += v
    ans = max(ans, now)

print(ans)