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

lis = []

for i in range(N):

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

    lis.append( A*2 + 0 )
    lis.append( B*2 + 1 )

lis.sort()

cnt = 0
ans = 0

for s in lis:

    if s % 2 == 0:
        cnt += 1
    else:
        cnt -= 1

    ans = max(ans , cnt)

print (ans)