fn main() {
    let mut nx = String::new();
    std::io::stdin().read_line(&mut nx).ok();
    let nx: Vec<usize> = nx.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let n = nx[0];
    let x = nx[1];
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    let s: Vec<usize> = s.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();

    let summary = s.iter().sum::<usize>();
    let diff = summary - x * (n-1);
    println!("{}", diff);
}