def max_overlap(intervals: list[tuple[int, int]]) -> int:
    events = []
    for l, r in intervals:
        events.append((l, 0))
        events.append((r, 1))

    res = 0
    cnt = 0
    # 同時刻ならイベント開始が先になるようにイベントソート
    for x, t in sorted(events):
        if t == 0:
            cnt += 1
        else:
            cnt -= 1
        res = max(res, cnt)

    return res


N, H = map(int, input().split())
imos = [0] * (H+10)
for _ in range(N):
    A, B = map(int, input().split())
    imos[A] += 1
    imos[B+1] -= 1

ans = 0
cnt = 0
for i in range(H):
    cnt += imos[i]
    ans = max(ans, cnt)

print(ans)