Working with functions

What will be displayed on the screen when the following code snippet is executed?

package main

import "fmt"

func main() {
 
 var X int = 020
 var Y float64 = 10.5
 var Z float64
 
 Z = float64(X)-float64(Y)
 fmt.Println(Z)
}

Options

1. 9.5
2. 4.5
3. 5.5
4. Error