Graphs (1) P56483

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

Input

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

Output

Write “yes” o “no” according to whether there is or not a path from $x$ to $y$.