uses Graph;

var
 grDriver: Integer;
 grMode: Integer;
 ErrCode: Integer;

 x1, x2, y1, y2, i, x: integer;
 ratio: real;
 y: real;

begin
 grDriver := Detect;
 InitGraph(grDriver, grMode,' ');
 ErrCode := GraphResult;
 if ErrCode = grOk then
 begin  { Do graphics }
 x1:=round(GetMaxX/2); y1:=round(GetMaxY/2);
 x2:=GetMaxX-50; y2:=GetMaxY;
 ratio:=(y2-y1)/(x2-x1);
 x:=x1; y:=y1;

 for i:=x1 to x2 do begin
     x:=x+1;
     y:=y+ratio;
     PutPixel(x,round(y),white);
 end;

   Readln;
   CloseGraph;
 end
 else
   Writeln('Graphics error:', GraphErrorMsg(ErrCode));
end.