the following program seems to be correct
(at least, it passed all the tests i've managed
to think out).But it gets WA#3.??
program garland;

{$APPTYPE CONSOLE}
var n,a,p,tp,dif:double;
    i:longint;

function f(x:double):double;
begin
 f:=x*x+tp*x+a;
end;

begin
 read(n,a);
 p:=-2*sqrt(a);
 dif:=10;
 for i:=1 to 1000 do begin
  dif:=dif/2;  tp:=p-dif;
  if (f(trunc(-tp/2))>=0) and (f(trunc(-tp/2)+1)>=0) then  p:=tp;
  end;
 tp:=p;
 write(f(n-1):0:2);
end.

Edited by author 28.02.2005 19:45