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

for i in range(H):
    imos[i+1] += imos[i]

print(max(imos))