What does this program print?

What does this program print?

fn main() {
    let mut values = vec![10, 20];
    let first = &values[0];
    println!("first: {first}");
    values.push(30);
    println!("all: {values:?}");
}

1. first: 10 all: [10, 20, 30]
2. It fails because first remains in lexical scope during push.
3. It panics if push reallocates the vector.
4. first: 30 all: [10, 20, 30]