program main
    integer n, h, a, b, i, watching, maximum
    integer, allocatable, dimension(:) :: watch
    read *, n, h
    allocate(watch(h+1))
    watch = 0
    do i = 1, n
        read *, a, b
        watch(a+1) = watch(a+1) + 1
        watch(b+2) = watch(b+2) - 1
    end do
    watching = 0
    maximum = 0
    do i = 1, h
        watching = watching + watch(i)
        maximum = max(maximum, watching)
    end do
    write (6, fmt='(I0)') maximum
end program main