If an integer is combined with the three numbers 1, 2, and 3 to form a formula through addition, subtraction, multiplication, and division (you can add parentheses), and the result is equal to 24, then this integer is called usable, then, in 4, 5, 6, 7 , 8, 9, 10 these seven numbers, how many integers are available.
如果一个整数，与1，2，3这三个数，通过加减乘除运算(可以添加括号)组成算式，结果等于24，那么这个整数称为可用的，那么，在4，5，6，7，8，9，10这七个数中，可用的整数有多少个．
<result>7</result>