avoid histogram to cover axis ticks

Dear Rooters,

I am plotting a filled tgraph, as the one in the small snippet here below, and I would like it not to cover the axis ticks, as it happens in the small example in fact. How can I obtain that?

Thank you very much, best regards,

pietro

TGraph p ;

p.SetPoint (0,1,0) ;
p.SetPoint (1,2,0) ;
p.SetPoint (2,2,2) ;
p.SetPoint (3,1,2) ;
p.SetPoint (4,1,0) ;

TCanvas c1 ;
c1.DrawFrame (1,-1 ,2, 3) ;
p.SetFillColor (kRed) ;
p.Draw ("F") ;