N, H = map(int, input().split())
streams = []
for _ in range(N):
    A, B = map(int, input().split())
    streams.append((A, 1))
    streams.append((B + 0.5, -1))

streams.sort(key=lambda x: x[0])
watching = 0
ans = 0
for time, diff in streams:
    watching += diff
    ans = max(ans, watching)

print(ans)