public static void needpeer(int need)
{
    StringBuffer ss = new StringBuffer();   while(true)
        { if(need % 2 ==0)
            {
                ss.append("2");  need = need /2 -1;  }else  {
                ss.append("1");  need = need/2;  } if(need == 0)
            {
                System.out.println(ss.reverse().toString());  return;  }
        }
}