Swap a b

print("Not using 3rd variable")

func swap( a: inout Int, b:inout Int) {
    a = a + b
    b = a - b
    a = a - b
}

func swapB(_ a: inout Int,_ b: inout Int) {
    a = a ^ b
    b = a ^ b
    a = a ^ b
}

var a:Int = 5, b = 7

swap(&a, &b)
print("number  is: ", a, b)

swapB( &a, &b)
print("swap again:",a, b)