set key graph 0.4,0.95
set label "3D" at graph 0.02,0.95
set xlabel "pieces"
set ylabel "time (seconds)
set terminal fig big thickness 1 fontsize 18
set pointsize 1
plot 'trial3D.plt' index 0 t "version-4" with linespoints pointtype 5
replot 'trial3D.plt' index 1 t "version-3" with linespoints pointtype 1
set output "trial3D.fig"
replot