You are asked to perform a 2-back test. You will see a sequence of letters. Your task is to respond with '+' (no quotation marks, just the plus sign) whenever the current letter is the same as the letter two letters before the current letter, and '-' (no quotation marks, just the minus sign) otherwise. Do not count '+' or '-' as letters. Only '+' and '-' are allowed responses.  No explanations are allowed; please don't output any extra words. The sequence will be presented one letter at a time. Now begins the task.

Next letter in sequence: z
