program read_n_plot
      real x(100),y(100)
      idummy=pgopen('/xwin')
      call pgenv(-10.0,10.0,-10.0,10.0,1,0)

      read(10,*)np
      do i=1,np
        read(10,*)x(i),y(i)
      end do

      call pgline(np,x,y)
      call pgclos
      end