module sub
	implicit none
contains
subroutine heapsort2(n,array,turn)
  implicit none
  integer,intent(in)::n
  integer,intent(out)::turn(1:n)
  integer,intent(inout)::array(1:n)
  
  integer::i,k,j,l,m
  double precision::t
  
  if(n.le.0)then
     write(6,*)"Error, at heapsort"; stop
  endif
  if(n.eq.1)return

  do i=1,N
     turn(i)=i
  enddo

  l=n/2+1
  k=n
  do while(k.ne.1)
     if(l.gt.1)then
        l=l-1
        t=array(l)
        m=turn(l)
     else
        t=array(k)
        m=turn(k)
        array(k)=array(1)
        turn(k)=turn(1)
        k=k-1
        if(k.eq.1) then
           array(1)=t
           turn(1)=m
           exit
        endif
     endif
     i=l
     j=l+l
     do while(j.le.k)
        if(j.lt.k)then
           if(array(j).lt.array(j+1))j=j+1
        endif
        if (t.lt.array(j))then
           array(i)=array(j)
           turn(i)=turn(j)
           i=j
           j=j+j
        else
           j=k+1
        endif
     enddo
     array(i)=t
     turn(i)=m
  enddo

  return
end subroutine heapsort2
end module sub



program main
	use sub
	implicit none
	integer :: N, M, i, j, counter
	integer, allocatable :: a(:), b(:), turn(:)
	read(*, *) N, M
	allocate(a(1:M))
	allocate(b(1:M))
	allocate(turn(1:M))
	do i = 1, M
		read(*, *) a(i), b(i)
	end do
	
	call heapsort2(M,a,turn)
	j = 1
	counter = 0
	do i = 1, M
	if(a(j) /= a(i)) then
		if(b(turn(j)) < a(i)) then
			counter = counter + 1
			j = i
		else if(b(turn(j)) > b(turn(i))) then
			j = i
		end if
	end if
	end do
	write(*, *) counter
end program main