等式数量.集合是基本的数学概念，集合中的元素是互不相同的。表示相等关系的式子叫做等式。给你一个包含有 N 个整数的集合，如果从集合中找到三个不同的整数 a,b,c， 使得a+b=c，那么我们说这个集合包含一个等式。-Equation number set is the basic mathematical concepts, elements in the collection are different from each other. Means that the equation is called the equation equal relationship. Give you a contains a collection of N integers, if different from the collection to find three integers a, b, c, such that a+ b = c, then we say that the collection contains an equation.