32. (5 points)
Sun Wukong plans to distribute peaches to 19 little monkeys, with each monkey getting $a$ peaches, and leaving $b$ peaches $(b<a)$ for himself. It turns out that two of the little monkeys have already left the Mountain of Flowers and Fruits, so Sun Wukong distributed the peaches to the remaining 17 little monkeys, with each monkey getting $(a+1)$ peaches, and leaving $(b+1)$ peaches for himself. Then $a=$ $\qquad$ .
$9$