integer function cbnt()
      implicit none

      include 'grid3_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 'grid3_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 'grid3_cbnt.inc'
      esel = 0.0
      val = eg_et(ielec)
      if ( val .ge. 5 ) then
        esel = val
      endif
      return
      end