Task: songer_civproc2

What follows is an opinion from a United States Court of Appeals.
Your task is to identify the second most frequently cited federal rule of civil procedure in the headnotes to this case. Answer "0" if less than two federal rules of civil procedure are cited. For ties, code the first rule cited.

PER CURIAM.
The appeal is from a judgment of conviction of robbery, in violation of D.C. Code § 22-2901, and is rested upon the admission of evidence now claimed to have been inadmissible. In view of all the circumstances of the case we think it is not one for the exercise of our discretion permitted by Rule 52(b), Fed.R. Crim.P.
Affirmed.

Question: What is the second most frequently cited federal rule of civil procedure in the headnotes to this case? Answer with a number.
Answer:

Answer: 0