arctan4.pas

arctan.zip

const
  zero=1e-7;
var
  x,a:longint;
  p,q:extended;
begin
  assign(input,'arctan.in');
  reset(input);
  readln(a);
  close(input);
  p:=a;
  p:=p*p+1;
  for x:=a downto 1 do begin
    q:=frac(p/x);
    if (q<zero)or(q+zero>1) then begin
      assign(output,'arctan.out');
      rewrite(output);
      writeln(p/x+x+a*2:0:0);
      close(output);
      halt
    end;
  end;
end.