No, they will be freshmen next year.

A top tree is a tree structure of "top clusters". Consider a connected subgraph on tree, if there are only two vertices which have edges with outside, we call the subgraph "top cluster". Top trees have very strong ability but the whole top trees are very hard to implement in the contest. Instead we often use a simplified version called "the subtree maintaining tricks of link/cut tree". You can learn more on https://en.wikipedia.org/wiki/Top_tree.