void first() {
   
   TCanvas *nut = new TCanvas("nut", "FirstSession",100,10,700,900);
   nut->Range(0,0,20,24);
   nut->SetFillColor(10);
   nut->SetBorderSize(2);

   TPaveLabel *pl = new TPaveLabel(3,22,17,23.7,"My first ROOT interactive session","br");
   pl->SetFillColor(18);
   pl->Draw();

   TText t(0,0,"a");
   t.SetTextFont(62);
   t.SetTextSize(0.025);
   t.SetTextAlign(12);
   t.DrawText(2,20.3,"ROOT is based on CINT, a powerful C/C++ interpreter.");
   t.DrawText(2,19.3,"Blocks of lines can be entered within {...}.");
   t.DrawText(2,18.3,"Previous typed lines can be recalled.");

   t.SetTextFont(72);
   t.SetTextSize(0.026);
   t.DrawText(3,17,"Root >  float x=5; float y=7;");
   t.DrawText(3,16,"Root >  x*sqrt(y)");
   t.DrawText(3,14,"Root >  for (int i=2;i<7;i++) printf(\"sqrt(%d) = %f\",i,sqrt(i));");
   t.DrawText(3,10,"Root >  TF1 f1(\"f1\",\"sin(x)/x\",0,10)");
   t.DrawText(3, 9,"Root >  f1.Draw()");
   t.SetTextFont(81);
   t.SetTextSize(0.018);
   t.DrawText(4,15,"(double)1.322875655532e+01");
   t.DrawText(4,13.3,"sqrt(2) = 1.414214");
   t.DrawText(4,12.7,"sqrt(3) = 1.732051");
   t.DrawText(4,12.1,"sqrt(4) = 2.000000");
   t.DrawText(4,11.5,"sqrt(5) = 2.236068");
   t.DrawText(4,10.9,"sqrt(6) = 2.449490");

   TPad *pad = new TPad("pad","pad",.2,.05,.8,.35);
   pad->SetFillColor(42);
   pad->SetFrameFillColor(33);
   pad->SetBorderSize(10);
   pad->Draw();
   pad->cd();
   pad->SetGrid();
   TF1 *f1 = new TF1("f1","sin(x)/x",0,10);
   f1->Draw();
   nut->cd();
}
