Given a math word problem, answer the following question. You might need to apply addition or subtraction mathematical operators on the numbers embedded in the text to answer the question and then only report the final numerical answer.
Q: 94 students signed up for computer classes . there were 24 second graders and 29 third graders . the rest of the students were 4 graders . how many 4 graders took computer classes ?
A:
41