integer function cbnt()
      implicit none

      include 'cbnt.inc'

      integer cut1
      real esel
      integer nsel, i, j, ih, imax, keep(20), ktmp
      real tmp, order(20)
      real p0, p1, p2, p3, eet, eeta, ephi
      real pt_4e, phi_4e, eta_4e, m4esq, m4e

      write(*,*) idnevt, run, event
      call hf1(1,1.0*run,1.0)
      call hf1(2,1.0*event,1.0)
      call hf1(3,1.0*event,1.0)
      call hf1(4,1.0*event,1.0)
      call hf1(5,1.0*event,1.0)
      call hf1(6,1.0*event,1.0)

* Electron info
* Without cuts.
      write(*,*) eg_nc, ' electrons'
      call hf1(101, 1.0*eg_nc, 1.0)
      nsel = 0
      do i = 1, eg_nc
        call hf1(102, eg_et(i), 1.0)
        call hf1(103, eg_eta(i), 1.0)
        call hf1(104, eg_phi(i), 1.0)
* Select electrons.
        tmp = esel(i)
        if ( tmp .gt. 0.0 ) then
          nsel = nsel + 1
          keep(nsel) = i
          order(nsel) = tmp
        endif
      enddo
      call hf1(111, 1.0*nsel, 1.0)
* Sort electrons.
      do i = 2, nsel
        do j = i-1, 1, -1
          if ( order(j+1) .le. order(j) ) goto 100
          tmp = order(j)
          ktmp = keep(j)
          order(j) = order(j+1)
          keep(j) = keep(j-1)
          order(j+1) = tmp
          keep(j+1) = ktmp
  100   enddo
      enddo
      imax = nsel
      if ( imax .gt. 4 ) then
        imax = 4
      endif
      do i = 1, imax
        ih = 100 + 10*i
        j = keep(i)
        call hf1(ih+2, eg_et(j), 11.0)
        call hf1(ih+3, eg_eta(j), 1.0)
        call hf1(ih+4, eg_phi(j), 1.0)
      enddo
* Loop over electrons and 4e mass from leading electrons.
      if ( nsel .ge. 4 ) then
        p0 = 0.0
        p1 = 0.0
        p2 = 0.0
        p3 = 0.0
        do i = 1, 4
          j = keep(i)
          eet = eg_et(j)
          eeta = eg_eta(j)
          ephi = eg_phi(j)
          p0 = p0 + eet*cosh(eeta)
          p3 = p3 + eet*sinh(eeta)
          p1 = p1 + eet*cos(ephi)
          p2 = p2 + eet*sin(ephi)
        enddo
        pt_4e = sqrt(p1*p1 + p2*p2)
        phi_4e = atan2(p2, p1)
*        eta_4e = atanh(p3/p0)
        m4esq = p0*p0 - pt_4e*pt_4e - p3*p3
        m4e = 0.0
        if ( m4esq .ge. 0.0 ) then
          m4e = sqrt(m4esq)
        endif
        call hf1(152, pt_4e, 11.0)
*        call hf1(153, eta_4e, 1.0)
        call hf1(154, phi_4e, 1.0)
        call hf1(155, m4e, 1.0)
      endif

*Exit
      cbnt = 1
      return
      end

* Cut 1 on event.
      integer function cut1()
      include 'cbnt.inc'
      cut1 = 0
      if ( eg_nc .ge. 4 ) then
        cut1 = 1
      endif
      return
      end

* Electron sorting function. Higher values will be placed
* ahead of lower ones. Anything <= 0 is rejected.
      real function esel(ielec)
      implicit none
      integer ielec
      real val
      include 'cbnt.inc'
      esel = 0.0
      val = eg_et(ielec)
      if ( val .ge. 5 ) then
        esel = val
      endif
      return
      end