Graphs (2) P37001

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 the value of $n$ and the $n$ names of the vertices. Then comes the value of $m$ and follow the $m$ arcs, made up by the name of two vertices, without repetitions nor autoloops. Then follows a pair of vertices $x,y$. You can assume that $x$ and $y$ belong to the graph.

Output

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