use std::collections::{BTreeSet, HashMap, HashSet, VecDeque};

use proconio::marker::Chars;

fn main() {
    proconio::input! {
        n: usize,
        a: [usize; n],
    }
    let mut a = VecDeque::from(a);
    a.iter_mut().for_each(|x| *x -= 1);
    for i in 0.. {
        while a[a.len() - 1] == a.len() - 1 {
            a.pop_back();
            if a.is_empty() {
                println!("{}", i);
                return;
            }
        }
        let max_index = a.iter().enumerate().max_by_key(|x| x.1).unwrap().0;
        let index = a
            .iter()
            .enumerate()
            .skip(max_index + 1)
            .max_by_key(|x| x.1)
            .unwrap()
            .0;
        eprintln!("{} {}", max_index, index);
        let value = a[index];
        a.remove(index);
        a.push_front(value);
        eprintln!("{a:?}");
    }
}