Basic Logic Mystery Cache

This is rudimentary logic that should be understandable to most evolved species.

A class at Starfleet Academy consists of 1,000 students using 1,000 lockers. On the first day of the term an instructor asks the first student to proceed along the row of lockers and open each one. He then asks the second student to proceed along the row and close every second locker. The third student is asked to go to every third locker and close it if it is open or open it if it is closed. The fourth is asked to go to the fourth locker and so on. The process is completed with the thousandth student.

How many lockers are open at the end? Let's call this answer "A".

Subtract the values beneath the underlines below from A. Then, fill in the blanks with the corresponding letter from the English language to solve the puzzle.