program dice
      implicit none
      integer i_answer, n, iseed
      real x, ran3
      external ran3

      iseed = 5

 100  write(*,*) 'Row a dice ? (1=Yes ; 0=No)'
      read(*,*) i_answer

      if ((i_answer.ne.0) .and. (i_answer.ne.1)) then
        write(*,*) '1 or 0 only, please.'
        goto 100 
      endif

c     if (i_answer.eq.0) stop('Good luck!') ! g77 does not support this.
      if (i_answer.eq.0) stop
     
      x = ran3(iseed)
      n = int(6*x)+1
      write(*,*) 'ran3( ) give you',x ,'    Dice shows', n

      goto 100

      end