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