with Ada.Text_IO;
with Ada.Integer_Text_IO;
with Ada.Float_Text_IO;
use Ada.Text_IO;
use Ada.Integer_Text_IO;
use Ada.Float_Text_IO;

procedure hoge is
 k: Integer;
 a: Integer;
 b: Integer;
 flag: Integer :=0;
begin
 get(k);
 get(a);
 get(b);
 for i in a..b loop
  if (i rem k)=0 then
   flag:=1;
  end if;
 end loop;
 if flag = 1 then
  put_line("OK");
 else
  put_line("NG");
 end if;
end hoge;