All the test I made up was ok.
but I can't pass test #1!
please halp me!
program gh;
type
 node=record
  v:boolean;
  w,e1,r:longint;
  x,e:array[1..100] of integer;
 end;
var
 a:array[1..10000] of node;
 d:array[1..200] of integer;
 s,f,g,h,j,k,l,m,n,i,d1:longint;
 procedure work(q:integer);
 var
  z,c,b,i,j:longint;
 begin
  a[q].w:=0;
  a[q].e1:=0;
  for i:=1 to a[q].r do
   begin
    if a[a[q].x[i]].v=true then
     begin
      if a[a[q].x[i]].w+1>a[q].w then
       begin
        a[q].w:=a[a[q].x[i]].w+1;
        a[q].e1:=a[q].e1+1;
        a[q].e[a[q].e1]:=a[q].x[i];
       end
     end
    else
     begin
      work(a[q].x[i]);
      if a[a[q].x[i]].w+1>a[q].w then
       begin
        a[q].w:=a[a[q].x[i]].w+1;
        a[q].e1:=1;
        a[q].e[a[q].e1]:=a[q].x[i];
       end
      else
       begin
        if a[a[q].x[i]].w+1=a[q].w then
         begin
          a[q].e1:=a[q].e1+1;
          a[q].e[a[q].e1]:=a[q].x[i];
         end;
       end;
     end;
   end;
  a[q].v:=true;
 end;
 procedure work1(q,z:integer);
 var
  c,j,c1,b1,i,b,k,l:longint;
 begin
  if (a[q].e1>=2) or (a[q].w=z+1) then
   begin
    writeln(q);
    halt;
   end
  else
   begin
    if a[q].w>z+1 then
     begin
      if a[q].w=z+2 then
       begin
        writeln(q,' ',a[q].e[1]);
        halt;
       end
      else
       begin
        c:=0;
        for i:=1 to a[q].r do
         if (a[a[q].x[i]].w+1<a[q].w) and (a[a[q].x[i]].w+1>c) then
          c:=a[a[q].x[i]].w;
        if c>z then
         z:=c;
        if a[q].w=z+2 then
         writeln(q,' ',a[q].e[1])
        else
         work1(a[q].e[1],z+1);
       end;
     end;
   end;
 end;



begin
 read(n);
 for i:=2 to n do
  begin
   read(s);
   a[s].r:=a[s].r+1;
   a[s].x[a[s].r]:=i;
  end;
 work(1);
 if a[1].e1>=2 then
   writeln(1)
 else
  begin
   f:=0;
   for i:=1 to a[1].r do
    if (a[a[1].x[i]].w+1>f) and (a[a[1].x[i]].w+1<a[1].w) then
     f:=a[a[1].x[i]].w;
   if f=a[1].w-2 then
     writeln(1,' ',a[1].e[1])
   else
    begin
     work1(a[1].e[1],f+1);
    end;
  end;
end.