mod io {
    #[macro_export]
    macro_rules! scan {
        ($r:expr, [$t:tt; $n:expr]) => ((0..$n).map(|_| scan!($r, $t)).collect::<Vec<_>>());
        ($r:expr, ($($t:tt),*)) => (($(scan!($r, $t)),*));
        ($r:expr, [u8]) => (io::scan($r).into_bytes());
        ($r:expr, $t:ty) => (io::scan($r).parse::<$t>().unwrap());
    }

    use std::io::{BufRead, ErrorKind};

    pub fn scan<R: BufRead>(r: &mut R) -> String {
        let mut res = Vec::new();
        loop {
            let buf = match r.fill_buf() {
                Ok(buf) => buf,
                Err(e) if e.kind() == ErrorKind::Interrupted => continue,
                Err(e) => panic!(e), 
            };
            let (done, used) = match buf.iter().position(u8::is_ascii_whitespace) {
                Some(i) => {
                    res.extend_from_slice(&buf[..i]);
                    (res.len() > 0, i + 1)
                }
                None => {
                    res.extend_from_slice(buf);
                    (false, buf.len())
                }
            };
            r.consume(used);
            if done || used == 0 {
                return res.into_iter().map(char::from).collect();
            }
        }
    }
}

use std::io::{BufRead, Write};

fn run<R: BufRead, W: Write>(reader: &mut R, writer: &mut W) {
    let (n, x) = scan!(reader, (usize, usize));
    let s = scan!(reader, [usize; n]);

    let sum = s.iter().sum::<usize>();
    let ans = sum - (n - 1) * x;
    writeln!(writer, "{}", ans).ok();
}

fn main() {
    let (stdin, stdout) = (std::io::stdin(), std::io::stdout());
    let mut reader = std::io::BufReader::new(stdin.lock());
    let mut writer = std::io::BufWriter::new(stdout.lock());
    run(&mut reader, &mut writer);
}