program f
      integer ls,le,cs,ce,c,l,i,j
      character*50 s,fn
      logical lex
      real,allocatable::a(:,:)
c     extracts columns from multiple files in F.LST
      if(iargc().ne.4)then
       write(6,*)' usage: f linestart lineend columnstart columnend'
      else
       call getarg(1,s)
       read(s,*)ls
       call getarg(2,s)
       read(s,*)le
       call getarg(3,s)
       read(s,*)cs
       call getarg(4,s)
       read(s,*)ce
       inquire(file='F.LST',exist=lex)
       if(lex)then
        open(9,file='F.LST',status='old')
        i=0
1       read(9,*,end=99,err=99)
        i=i+1
        goto 1
99      close(9)
        
c       write(6,*)i,' files in F.LST'

        if(i.gt.0)then
         n=le-ls+1
         nc=ce-cs+1
         m=nc*i
         allocate(a(n,m))

c        write(6,*)'matrix ',n,' x ',m

         open(9,file='F.LST',status='old')
         do 2 j=1,i
         read(9,'(a)')fn

c        write(6,*)fn

         open(12,file=fn)
         do 3 l=1,ls-1
3        read(12,*)

         do 4 l=1,le-ls+1
         jj=(j-1)*nc
4        read(12,*)(a(l,jj+1),c=1,cs-1),(a(l,jj+c),c=1,nc)

2        close(12)
         close(9)

         do 5 l=1,n
5        write(6,*)(a(l,c),c=1,m)

        else
         write(6,*)'nothing in F.LST'
        endif
       else
        write(6,*)'F.LST does not exist'
       endif
      endif
      end