Latex. tableofcontents with titlesec package, add extra mark after list of content

documentclass[a4paper,14pt,twoside]{extreport}

begin{document}
    tableofcontents
    chapter{First chapter}
    section{First section}
    section{Second section}
    chapter{Second chapter}
    section{First section}
    section{Second section}
end{document}

The result of tableofcontents of standard latex command creates contents like this:

But I like add some extra words (marks) which are in circle before (after) like this:

documentclass[a4paper,14pt,twoside]{extreport}

usepackage{tocloft}
renewcommand*{cftsecpresnum}{S}


begin{document}
    tableofcontents
    chapter{First chapter}
    section{First section}
    section{Second section}
    chapter{Second chapter}
    section{First section}
    section{Second section}
end{document}