object Hello extends App {
var s1 = Set(-10, 5 , 1 , 2 , 3 , 4 ,5)
var s2 = Set(-2, 4 , 5 , 6 , 7 , 8)
s1 = s1 + 9
s2 = s2+ 9 + 10
s1.drop(2)
s2.dropRight(3)
if(s1.contains(4) && s2.contains(4))
println("Yes")
else
println("No")
println(s1.&(s2)) //s1和s2交集
println(s1++(s2)) //s1和s2并集
println(s1.diff(s2)) //s1和s2差集
println(s1.max)
println(s2.min)
}