N,H = map(int,input().split())

lis = []

for i in range(N):

    A,B = map(int,input().split())

    lis.append( (A,0) )
    lis.append( (B,1) )

lis.sort()

cnt = 0
ans = 0

for _,s in lis:

    if s == 0:
        cnt += 1
    else:
        cnt -= 1

    ans = max(ans , cnt)

print (ans)