program lines4
   implicit none
   call init
   call viewport(0.2,0.2,0.8,0.8)
   call xyworld(0.0,0.0,1.0,1.0)
   call linety(1)
   call linewidth(2.0)
   call setgray(0.0)
   call newpath
   call plot(0.1,0.1,3)
   call plot(0.9,0.1,2)
   call stroke
   call setgray(0.1)
   call newpath
   call plot(0.1,0.2,3)
   call plot(0.9,0.2,2)
   call stroke
   call setgray(0.2)
   call newpath
   call plot(0.1,0.3,3)
   call plot(0.9,0.3,2)
   call stroke
   call setgray(0.3)
   call newpath
   call plot(0.1,0.4,3)
   call plot(0.9,0.4,2)
   call stroke
   call setgray(0.4)
   call newpath
   call plot(0.1,0.5,3)
   call plot(0.9,0.5,2)
   call stroke
   call setgray(0.5)
   call newpath
   call plot(0.1,0.6,3)
   call plot(0.9,0.6,2)
   call stroke
   call setgray(0.6)
   call newpath
   call plot(0.1,0.7,3)
   call plot(0.9,0.7,2)
   call stroke
   call setgray(0.7)
   call newpath
   call plot(0.1,0.8,3)
   call plot(0.9,0.8,2)
   call stroke
   call setgray(0.8)
   call newpath
   call plot(0.1,0.9,3)
   call plot(0.9,0.9,2)
   call stroke
   call fin
   stop
   end