#[cfg(debug_assertions)]
const LENGTH: usize = 5;
#[cfg(not(debug_assertions))]
const LENGTH: usize = 3_017_957;

fn main() {
    let builder = std::thread::Builder::new().stack_size(100_000_000);
    let handle = builder.spawn(part_1).unwrap();
    handle.join().unwrap();
}

fn part_1() {
    let mut pointer = 0;

    let mut next = [0; LENGTH];

    for (idx, val) in next.iter_mut().enumerate() {
        *val = (idx + 1) % LENGTH;
    }

    loop {
        next[pointer] = next[next[pointer]];

        pointer = next[pointer];

        // only one elf left
        if next[pointer] == pointer {
            println!("{}", pointer + 1);
            break;
        }
    }
}