N, H = map(int, input().split())
imos = [0] * (H + 2)
for _ in range(N):
    a, b = map(int, input().split())
    imos[a] += 1
    imos[b + 1] -= 1
for i in range(H):
    imos[i + 1] += imos[i]
print(max(imos))