use proconio::input;
use std::collections::HashMap;
use std::collections::BTreeSet;
use std::ops::ControlFlow::Break;
fn main(){
    input!{
        n:usize,mut m:usize,
    }
    let mut vec:Vec<usize>=Vec::new();
    for i in (0..n){
        vec.push(i+1);
    }
    for i in (0..m){
        input!{
            c:usize,
        }
        for j in (1..c).rev(){
            vec.swap(j,j-1);
        }
    }
    print!("{}",vec[0])
}