Given a tree of $n$ nodes, your task is to find a centroid , i.e., a node such that when it is appointed the root of the tree, each subtree has at most $\lfloor n/2 \rfloor$ nodes.
The first input line contains an integer $n$ : the number of nodes. The nodes are numbered $1,2,…,n$ .
Then there are $n-1$ lines describing the edges. Each line contains two integers $a$ and $b$ : there is an edge between nodes $a$ and $b$ .
Print one integer: a centroid node. If there are several possibilities, you can choose any of them.