var a:integer;

begin

readln(a);

if (a<0) then a:=sqr(a);

writeln(a) else writeln('Error');

end.

type Cl = class
  a:integer;
  constructor Create(b:integer);
  procedure SetVal(b:integer);
  function GetVal:integer;
  procedure Sq;
end;

constructor Cl.Create(b:integer);
begin
  a := b;
end;

procedure Cl.SetVal(b:integer);
begin
  a := b;
end;

function Cl.GetVal:integer;
begin
  GetVal := a;
end;

procedure Cl.Sq;
begin
  if a < 0 then
    writeln('a ^ 2 = ', a * a)
  else
    writeln('Error');
end;


var
  Obj:Cl;
  a :integer;
begin
  write('a = ');
  readln(a);
  Obj := Cl.Create(a);
  Obj.Sq;
  Readln;
  Obj.Destroy;
end.