<image>Given that \( f(x) \) is a function defined on \( (0, +\infty) \), for any \( m > 0 \) and \( n > 0 \), it holds that \( f(m \cdot n) = f(m) + f(n) - 2 \). Furthermore, for \( x > 1 \), \( f(x) > 2 \). Let \( f(x) \)'s maximum value on \([, 10]\) be \( P \) and the minimum value be \( Q \). Then \( P + Q = ____ \).