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

fn get_lines() -> Vec<String> {
    let stdin = io::stdin();
    let lines: Vec<String> = stdin.lock().lines().map(|l| l.unwrap()).collect();
    return lines;
}

fn main(){
    let s = &get_lines();
    let n: i32 = s[0].parse().unwrap();
    let mut a = s[1].split(' ').map(|x| x.parse::<i32>().unwrap()).rev();
    a.position(|x| x == n);
    let mut c = n - 1;
    for x in a {
        if x == c {
            c -= 1;
        }
    }
    println!("{}", c);
}