const maxn=301; maxm=601; maxx=10001;
var
 add:boolean;
 f:array[0..maxm,1..2] of longint;
 a:array[0..maxm,0..maxn] of longint;
 fa:array[0..maxx] of longint;
 link:array[0..maxn] of longint;
 n,m,i,j,x,y,xx,yy,t,max:longint;
 v:array[0..maxn] of boolean;
 function find(k:longint):boolean;
 var i:longint;
 begin
  for i:=1 to a[k,0] do
   if not v[a[k,i]] then
    begin
     v[a[k,i]]:=true;
     if (link[a[k,i]]=0) or (find(link[a[k,i]])) then
      begin
       link[a[k,i]]:=k;
       exit(true);
      end;
    end;
  exit(false);
 end;
 function sf(k:longint):longint;
 begin
  if fa[k]<>k then fa[k]:=sf(fa[k]) else exit(k);
  sf:=fa[k];
 end;
begin
 assign(input,'coinmn.in'); reset(input);
 assign(output,'coinmn.out'); rewrite(output);
 readln(n);
 while n<>0 do
  begin
   m:=0;
   fillchar(a,sizeof(a),0);
   fillchar(link,sizeof(link),0);
   for i:=1 to n do
   begin
    xx:=-1; yy:=-1;
    for j:=1 to 2 do
     begin
      read(x,y);
      if x>y then //jh
       begin
        t:=x; x:=y; y:=t;
       end;
      if (xx=x) and (yy=y) then break;//panchong
      add:=true;
      for t:=1 to m do
       if (f[t,1]=x) and (f[t,2]=y) then
        begin add:=false; inc(a[t,0]); a[t,a[t,0]]:=i; break; end;
      xx:=x; yy:=y;
      if add then
       begin
        inc(m);
        f[m,1]:=x; f[m,2]:=y;
        inc(a[m,0]); a[m,a[m,0]]:=i;
       end;
     end;
   end;
   for i:=0 to maxx do fa[i]:=i;
   j:=0; fillchar(v,sizeof(v),#0);
   for i:=1 to m do
    begin
     fillchar(v,sizeof(v),#0);
     if find(i) then
     if sf(f[i,1])<>sf(f[i,2]) then
      begin
       fa[sf(f[i,1])]:=sf(f[i,2]);
       inc(j);
      end;
     end;
   writeln(j*2);
   read(n);
  end;
  close(input); close(output);
end.