$4.$ The United States Commission of Southern California Universities $($USC$-$SCU$)$ is researching the impact of class rank on student performance. For this research, they want to find a list of students ordered by GPA containing every student in California. However, each school only has an ordered list of its own students sorted by GPA and the commission needs an algorithm to combine all the lists. Design an efficient algorithm with running time O$($m log n$)$ for combining the lists, where m is the total number of students across all colleges and n is the number of colleges.