const
   limit        =1000;

type
   Tnode        =record
                     id         :integer;
                     dig        :extended;
                 end;

var
   s            :array[1..limit] of Tnode;
   n            :integer;

procedure init;
var
   x,y,bx,by    :extended;
   i            :integer;
begin
    read(bx,by,n);
    for i:=1 to n do
     with s[i] do
      begin
        read(x,y,id);
        x:=x-bx;y:=y-by;dig:=abs(y)/sqrt(x*x+y*y);
        if y>0 then
           if x>0 then dig:=1-dig
           else dig:=3+dig
        else if x>0 then dig:=1+dig
             else dig:=3-dig
      end;
end;

procedure sift(p,tot:integer);
var
   i,q          :integer;
   d            :extended;
begin
    i:=s[p].id;d:=s[p].dig;
    while true do
    begin
        q:=p+p;
        if (q<tot) and (s[q].dig<s[q+1].dig) then inc(q);
        if (q>tot) or (s[q].dig<d) then begin s[p].id:=i;s[p].dig:=d;exit;
                                        end;
        s[p]:=s[q];p:=q;
    end;
end;

procedure work;
var
   temp         :Tnode;
   i            :integer;
begin
    for i:=n div 2 downto 1 do sift(i,n);
    for i:=n downto 1 do
    begin
        temp:=s[i];
        s[i]:=s[1];
        s[1]:=temp;
        sift(1,i-1);
    end;
end;

procedure out;
var
   i            :integer;
begin
    writeln(0);
    for i:=1 to n do writeln(s[i].id);
    writeln(0);
end;

BEGIN
    init;
    work;
    out;
END.

what about this case:

0 0
3
5 1 1
4 2 2
-8 1 3