Consider the following CPU scheduling result in a single-processor system (Gantt chart): $P_1$ runs from 0 to 2 ms, $P_2$ from 2 to 3 ms, $P_3$ from 3 to 8 ms, $P_4$ from 8 to 12 ms, $P_5$ from 12 to 18 ms. If all the five processes complete within 18 ms, which statement(s) are correct?