with Ada.Integer_Text_IO;
procedure Eukl is
   A, B : Natural;
   Tmp: Natural;
begin
   Ada.Integer_Text_IO.Get( A );
   Ada.Integer_Text_IO.Get( B );
   while B /= 0 loop
      Tmp := A mod B;
      A := B;
      B := Tmp;
   end loop;
   Ada.Integer_Text_IO.Put( A );
end Eukl;