52. Xiao Fei's class forms a rectangular array for morning exercises. There is 1 classmate to Xiao Fei's left, and 2 classmates to his right. Counting from the front, he is the 6th, and counting from the back, he is the 5th. Therefore, the total number of students in Xiao Fei's class is. $\qquad$
Reference answer: 40