program SQ;
 
{$mode delphi}
 
uses
  SysUtils;
 
function sumOfDigits(n : integer) : Integer;
var s : string;
    k : Byte;
Begin
  s := IntToStr(n);
  Result := 0;
  for k := 1 to Length(s) do
    Result := Result + StrToInt(s[k]);
End;
 
var K, A, B, i, sqr_i, res : Integer;
 
begin
  Readln(a, b, K);
  res := 0;
  for i:=Round(Sqrt(a)) to Round(Sqrt(b)) do begin
    sqr_i := Sqr(i);
    if (sqr_i>=a) and (Sqr_i<=b) and (sumOfDigits(sqr_i) mod K = 0) then begin
      res := res + 1;
    end;
  end;
  Writeln(res);  
end.
 

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