Pulkit is ranked 18th from the top, which means there are 17 students above him.
Pulkit is ranked 37th from the bottom, which means there are 36 students below him.
The total number of students in the class consists of:
Students above Pulkit: 17
Pulkit himself: 1
Students below Pulkit: 36
Total number of students =17+1+36
Total number of students =54
Therefore, there are 54 students in the class.