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

use proconio::marker::Chars;

fn main() {
    proconio::input! {
        n: usize,
        a: [usize; n],
    }
    let mut x = n;
    let s = a
        .iter()
        .rev()
        .filter(|&a| {
            if *a == x {
                x -= 1;
                true
            } else {
                false
            }
        })
        .count();
    println!("{}", n - s);
}