Let \( f(x) \) be a quadratic polynomial with leading coefficient \( 1 \) such that \( f(0) = p, \; p \neq 0, \) and \( f(1) = \dfrac{1}{3} \). If the equations \( f(x) = 0 \) and \( fof of of(x) = 0 \) have a common real root, then \( f(-3) \) is equal to \( \_ \_ \_ \_ \_ \_ \).
