use std::io::*;
use std::collections::VecDeque;

fn main() {
    let mut s = String::new();
    std::io::stdin().read_to_string(&mut s).ok();
    let mut itr = s.trim().split_whitespace();
    let n: usize = itr.next().unwrap().parse().unwrap();
    let mut cards: VecDeque<usize> = (1..=n).collect();
    let _m: usize = itr.next().unwrap().parse().unwrap();
    itr.map(|x| x.parse::<usize>().unwrap()).for_each(|i| {
        let buf = cards.remove(i - 1).unwrap();
        cards.push_front(buf);
    });
    println!("{}", cards[0]);
}