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

    if n < 4 {
        if (0..n).filter(|&i| p[i] == i+1).count() == n {
          println!("0");
            return;
        } else {
            while *p.last().unwrap() == p.len() {
                p.pop();
            }
        }
    }
    let n = p.len();
    let summary = p.iter().sum::<usize>();
    let idx = (0..n).filter(|&i| p[i] == n).nth(0).unwrap() + 1;
    println!("{}", summary - 2*idx);
}