N, H = map(int, input().split())
AB = [list(map(int, input().split())) for _ in range(N)]

imos = [0]*(H+1)
for A, B in AB:
    imos[A] += 1
    imos[B+1] -= 1
for i in range(1, H+1):
    imos[i] += imos[i-1]

print(max(imos))