import java.util.Scanner;
import java.util.ArrayList;
import java.util.InputMismatchException;

public class JengaSort {
    static Scanner scanner = new Scanner(System.in);
    public static void main(String[] args){
        int N = Input(1 , 100000);
        ArrayList<Integer> High = new ArrayList<>();
        for(int i = 0 ; i < N ; i++){
            High.add(Input(1,N));
        }
        int Result = Processing(N,High);
        System.out.println(N - Result);
        
    }
    
    public static int Input(int Min , int Max){
        int Number = scanner.nextInt();
        try{
            if(Number < Min || Number > Max){
                System.out.println(Min + "以上" + Max + "以下で入力してください");
                System.exit(0);
            }
        }catch(InputMismatchException e){
            System.out.println("数字を入力してください");
            System.exit(0);
        }catch(Exception E){
            System.out.println("予期せぬエラーです");
            System.exit(0);
        }
        return Number;
    }
    
    public static int Processing(int N , ArrayList<Integer> High){
        int Count = 0;
        int Match = N;
        for(int i = N - 1 ; i >= 0 ; i--){
            if(High.get(i) == Match){
                Count++;
                Match--;
            }
        }
        //System.out.println(Count);
        return Count;
    }
}