NIMCET 2015 Paper

A professor has 24 text books on computer science and is concerned about their coverage of the topics $(P)$ compilers, $(Q)$ data structures and $(R)$ operating systems. The following data gives the number of books that contain material on these topics : $n(P)=8,n(Q)=13,n(R)=13,n(P\cap Q)=3,n(P\cap Q\cap R)=2$, where $n(x)$ is the cardinality of the set $x$, then, the number of text books that have no material on compiler is: