4. Teacher Wang decorated the classroom with stickers, arranging them in a row. She first stuck 15 Bing Dwen Dwen stickers, and then inserted 2 Shuey Rhon Rhon stickers between each adjacent pair of Bing Dwen Dwen stickers. Teacher Wang stuck a total of $\qquad$ stickers.
\begin{tabular}{c}
4 \\
\hline 43
\end{tabular}