with Ada.Text_IO, Ada.Integer_Text_IO;
 use Ada.Text_IO, Ada.Integer_Text_IO;

procedure main is
   K: Integer;
   A: Integer;
   B: Integer;
begin
   get(K);
   get(A);
   get(B);
   for i in A..B loop
      if (i rem K = 0) then
        put_line("OK");
        return;
      end if;
   end loop;
   put_line("NG");
end main;