DEFINITION
Greatest Integer Function [...] is a function that gives
the greatest integer less than or equal to a given number.
SOLUTION
pi = 3.14...
pi/2 = 1.57...
The greatest integer number, lesser than or equal to pi/2 = 1.57..., is 1.
THEREFORE, f(pi) = [pi/2] = [1.57...] = 1. ANSWER