Rooted Tree Graph

Suppose that we have a rooted tree $T$ with vertices $1, \ldots, n$. We construct an undirected ancestor graph $G$ of $T$ with the same set of vertices. A pair of distinct vertices $v, u$ is adjacent in $G$ if and only if $v$ is an ancestor of $u$ in $T$, or vice versa. You are given a graph $G$ with $n$ vertices. Construct any rooted tree $T$ such that $G$ is the ancestor graph of $T$, or determ