Unweighted Paths on NetworkX X25538

Given a directed graph with $n$ vertices and $m$ arcs, we wish to know if there is a directed path between two given vertices.

Input

Input starts with $n$ and $m$. Then follow $m$ pairs $u,v$, with $u \ne v$, indicating an arc from $u$ to $v$. We have that $0 \leq u < n$ and $0 \leq v < n$ and that there are no repeated arcs. Then follows a pair $x$, $y$ with $0 \leq x < n$ and $0 \leq y < n$.

Output

Write “yes” or “no” according to whether there is a path from $x$ to $y$.

Observation

We are authorized to employ the NetworkX library.