n,h=map(int,input().split())
imos=[0]*(h+1)
for _ in range(n):
    a,b=map(int,input().split())
    imos[a]+=1
    imos[b+1]-=1
for i in range(1,h+1):
    imos[i]+=imos[i-1]

print(max(imos))