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

    let n: u8 = stdin.next().unwrap().parse().unwrap();
    let m: usize = stdin.next().unwrap().parse().unwrap();
    let a: Vec<u8> = (0..m)
        .map(|_| stdin.next().unwrap().parse().unwrap())
        .collect();

    println!("{}", output(solve(n, a)));
}

fn solve(n: u8, a: Vec<u8>) -> u8 {
    let mut cards = (1..=n).collect::<std::collections::VecDeque<_>>();
    a.into_iter().for_each(|a| {
        let c = cards
            .drain(((a - 1) as usize)..=((a - 1) as usize))
            .next()
            .unwrap();
        cards.push_front(c);
    });
    *cards.front().unwrap()
}

fn output(ans: u8) -> u8 {
    ans
}