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