import graph; unitsize(1cm); ylimits(min=-3,max=4); yaxis("$y_1$", Ticks("%", new real[]{0,1,sqrt(2)},Size=1mm,1bp+red), Arrow); labely("$\sqrt{2}$",(0,sqrt(2)),E); yaxis(axis=XEquals(2.2), Label("$y_2$",align=NE), Ticks(begin=false,end=false, beginlabel=false,endlabel=false, pTick=blue,ptick=gray), Arrow); yaxis(axis=XEquals(4.4), Label("$y_3$",align=NE), ymin=-1,ymax=3.5,red, Ticks(step=.5,end=false), Arrow); yaxis(axis=XEquals(6.6), Label("$y_4$",align=NE), RightTicks(Step=2,step=.5), Arrow); shipout(bbox(2mm,Fill(white)));