var n,i:longint;
    a:array[0..100]of longint;
    f:boolean;
    t:double;
begin
  readln(n);
  for i:=1 to n do
    read(a[i]);
  t:=a[2]-a[1];
  f:=true;
  for i:=3 to n do
    if a[i]-a[i-1]<>t then
    begin
      f:=false;
      break;
    end;
  if f then
  begin
    writeln('dengcha');
    halt;
  end;
  t:=a[2]/a[1];
  f:=true;
  for i:=3 to n do
    if a[i]/a[i-1]<>t then
    begin
      f:=false;
      break;
    end;
  if f then
  begin
    writeln('dengbi');
    halt;
  end;
  writeln('no');
end.
/**************************************************************
	Problem: 1806
	User: admin
	Language: Pascal
	Result: Wrong Answer
****************************************************************/