Solution
= Solution
\b[False.] Take two <vertices> $u,v$ with both directed <edges>, and start <depth-first search> at $v$. The timestamps are $d[v]=1$, $d[u]=2$, $f[u]=3$, $f[v]=4$. There is an <edge>, hence a <directed path>, from $u$ to $v$, but $f[u]<f[v]$. Reaching a gray ancestor does not make the ancestor finish first.