program ap
  implicit none
  integer :: ans, larg, cnttai,in
  integer :: h, w , n, i, sumers, csum, err, j, jc(1), X, L
  integer,allocatable,dimension(:) :: xmax, xmin
  integer,allocatable,dimension(:) ::  cnt,ers
  integer,allocatable,dimension(:,:) :: taio

  read(*,*) n

!  allocate( X(n+1) )
!  allocate( L(n+1) )
  allocate( xmax(n+1) )
  allocate( xmin(n+1) )
  allocate( cnt(n+1) )
  allocate( ers(n+1) )
  allocate( taio(n+1,n+1) )
  
  do i=1,n
     read(*,*) X, L
     xmax(i)=X+L
     xmin(i)=X-L
  enddo

  ers(:)=0
  cnt(:)=0
  csum=0
  taio(:,:)=0
  do i=1,n
     do j=1,n
        if(i.eq.j) goto 300
        w=0
        if(xmax(i).gt.xmin(j).and.xmax(i).le.xmax(j)) then
           w=w+1
        endif
        if(xmin(i).lt.xmax(j).and.xmin(i).ge.xmin(j)) then
           w=w+1
        endif
        
        
        if(w.eq.2) then
           ers(j)=1
           taio(j,i)=1
        elseif(w.eq.1) then
           taio(j,i)=1
        endif
        
        300 continue
     enddo
  enddo
  do j=1,n
     do i=1,n
        csum=csum+taio(j,i)
     enddo
  enddo
  err=0

  do j=1,n
     if(ers(j).eq.1) then
        do i=1,n
           cnttai=cnttai+taio(j,i)
        enddo
        csum=csum-cnttai*2
        taio(j,:)=0
        taio(:,j)=0
        err=err+1
     endif
  enddo

  
  
  if(sum(taio).le.0) goto 400
  
  do i=1,n

     cnt(:)=0
     do j =1,n
        do in=1,n
           cnt(j)=cnt(j)+taio(j,in)
        enddo
     enddo

     jc=maxloc(cnt)
     err=err+1
     taio(jc(1),:)=0
     taio(:,jc(1))=0
     larg=0
     do j =1,n
        do in=1,n
           larg=larg+taio(j,in)
        enddo
     enddo
     
     if(larg.le.0) goto 400

  enddo
400 continue
  
  print *,  n-err
  
end program ap
