What will be the output of the following R code?

> printmessage2 <- function(x) {
+     if(is.na(x))
+             print("x is a missing value!")
+     else if(x > 0)
+             print("x is greater than zero")
+     else
+             print("x is less than or equal to zero")
+     invisible(x)
+ }
> printmessage2(NA)