import java.util.*;
import java.math.*;

public class Main {
    private static Scanner sc = new Scanner(System.in);
    public static void main(String[] args) throws Exception {
        int n = sc.nextInt();
        int[] ary = new int[n+1];
        for (int i = 1;i <= n;i++) {
            ary[i] = sc.nextInt();
        }
        int ret = 0;
        int max = n;
        for (int i = n;i > 0;i--) {
            if (ary[i]==max) {
                ret++;
                max--;
            }
        }
        System.out.println(n-ret);
    }
}