var norm,inv:array[1..1010]of longint;
    n,i,bad:integer;


begin


  readln(n);

  while n<>0 do
  begin

    for i:=1 to n-1 do
    begin
      read(norm[i]);
      inv[norm[i]]:=i;

    end;

    readln(norm[n]);

    inv[norm[n]]:=n;

    bad:=0;

    for i:=1 to n do if inv[i]<>norm[i] then bad:=1;

    if bad=1 then writeln('ambiguous')
    else writeln('not ambiguous');



    readln(n);

  end;





end.