fn main() {
    let stdin = std::io::read_to_string(std::io::stdin().lock()).unwrap();
    let mut stdin = stdin.split_ascii_whitespace();

    let n: u32 = stdin.next().unwrap().parse().unwrap();
    let start: u32 = stdin.next().unwrap().parse().unwrap();
    let end: u32 = stdin.next().unwrap().parse().unwrap();
    let stones: Vec<u32> = (0..n)
        .map(|_| stdin.next().unwrap().parse().unwrap())
        .collect();

    use std::io::Write;
    std::io::stdout()
        .lock()
        .write_all(output(solve(start, end, stones)).as_bytes())
        .unwrap();
}

fn prepare(stones: Vec<u32>) -> Vec<Vec<u32>> {
    let mut groups = vec![Vec::new(); 31];
    stones
        .into_iter()
        .for_each(|s| groups[s.count_ones() as usize].push(s));
    groups
}

fn solve(start: u32, end: u32, stones: Vec<u32>) -> Option<u32> {
    let mut stones = prepare(stones);
    let mut q = std::collections::VecDeque::new();
    q.push_back((start, 0));
    while let Some((cur_pos, cur_dist)) = q.pop_front() {
        if (cur_pos ^ end).count_ones() == 1 {
            return Some(cur_dist);
        }
        if cur_pos.count_ones() >= 1 {
            stones[(cur_pos.count_ones() - 1) as usize] = stones[(cur_pos.count_ones() - 1) as usize]
                .iter()
                .filter_map(|&next| match (cur_pos ^ next).count_ones() == 1 {
                    true => {
                        q.push_back((next, cur_dist + 1));
                        None
                    }
                    false => Some(next),
                })
                .collect();
        }
        if cur_pos.count_ones() <= 29 {
            stones[(cur_pos.count_ones() + 1) as usize] = stones[(cur_pos.count_ones() + 1) as usize]
                .iter()
                .filter_map(|&next| match (cur_pos ^ next).count_ones() == 1 {
                    true => {
                        q.push_back((next, cur_dist + 1));
                        None
                    }
                    false => Some(next),
                })
                .collect();
        }
    }
    None
}

fn output(ans: Option<u32>) -> String {
    match ans {
        Some(ans) => ans.to_string(),
        None => String::from("-1"),
    }
}