fn main() {
    let x: u64 = (1 << (63-1))-1;
    let x2: u64 = (1 << (63-0))-1;

    println!("x: {:064b}", x);
    println!("leading_zeros: {}\n", x.leading_zeros());

    println!("x: {:064b}", x2);
    println!("leading_zeros: {}", x2.leading_zeros());
}