<image>Given that \textit{x} and \textit{y} satisfy the constraint conditions , and the objective function \textit{z} = \textit{abx} + \textit{y} achieves a maximum value of 8, then the minimum value of \textit{a} + \textit{b} is _______. Both \textit{a} and \textit{b} are greater than 0.