If \( R \) is the smallest equivalence relation on the set \( \{1, 2, 3, 4\} \) such that \( \{(1,2),(1,3)\} \subset R \), then the number of elements in \( R \) is ______.
\( 10 \)
\( 8 \)
\( 12 \)
\( 15 \)