Let f : R → R defined by \(\rm f(x) \left\lbrace \begin{matrix} \rm 2x \ ; \ x > 3 \\\ \rm x^2 \ ; \ 1 < x \le 3 \\\ \rm 3x \ ; \ x \le 1 \end{matrix}\right.\) then f(-1) + f(2) + f(4) is