The Following Table Shows the Results of a Survey of Authors

The following table shows the results of a survey of authors by a fictitious publishing company. $$\begin{array} { | l | l | l | l | } \hline & \text { New Authors } & \begin{array} { l } \text { Established } \\\text { Authors }\end{array} & \text { Total } \\\hline \text { Successful } & 4 & 25 & 29 \\\hline \text { Unsuccessful } & 9 & 55 & 64 \\\hline \text { Total } & 13 & 80 & 93 \\\hline\end{array}$$ ​
Consider the following subsets of the set S of all authors represented in the table: C, the set of successful authors; U, the set of unsuccessful authors; N, the set of new authors; and E, the set of established authors. Find the number of elements that set $C \cap N ^ { \prime }$ contains. $n \left( C \cap N ^ { \prime } \right) =$ __________