Here is a set of basic questions producing integer or string outputs. Answer them and format the result precisely with the JSON instructions provided:

Question 0 (Question id: q_7INKrzP):
Your job is to return the last character of a string as a string. For example, the last char of "hello" is "o". Return the last character of the following string: "factories"

Question 1 (Question id: q_QfJE):
How many times does the letter "d" appear in the text: "used on"? Respond with an integer.

Question 2 (Question id: q_HXtU):
Your job is to return the last character of a string as a string. For example, the last char of "hello" is "o". Return the last character of the following string: "opponents"

Question 3 (Question id: q_5zFMr):
Determine the value of a that satisfies: 15 - 4*a = -21 Respond with an integer.



Produce a JSON object whose top-level keys are the question ids.

The value for each key should be an object that contains the answer in the field 'answer'.
If the response to a question is an integer that is even, add the field 'additional_answer_info' containing 'half_answer' (answer ÷ 2) and 'double_answer' (answer × 2).

Now provide the result JSON using the described format.

{"ground_truth": {"q_7INKrzP": {"answer": "s"}, "q_QfJE": {"answer": 1}, "q_HXtU": {"answer": "s"}, "q_5zFMr": {"answer": 9}}}