subroutine chars(c1,c2)
      character*(*) c1,c2,c3*10
      l=len(c1)
      write(*,10)l
   10 format(1h ,10hlength c1=,i3)
      c3=c1//c2
      write(*,20)c3
      c2=c3
   20 format(1h ,a20)
      return
      end
      character*10 mess
      mess=' you'
      call chars('hello',mess)
      write(*,30)mess
   30 format(1h ,a20)
      stop
      end