Does this program compile, and what does it print?

Does this program compile, and what does it print?

use std::cell::RefCell;

fn main() {
    let values = RefCell::new(vec![10, 20]);
    let first = values.borrow()[0];
    values.borrow_mut().push(30);
    println!("{first}: {:?}", values.borrow());
}

1. 10: [10, 20, 30]
2. It panics because the first borrow lasts to the closing brace.
3. 30: [10, 20, 30]
4. It fails because RefCell cannot contain Vec.