import java.util.*;

public class Exercises1 {

	private static Scanner sc;

	public static void main(String[] args) {
		sc = new Scanner(System.in);

		int num = sc.nextInt();
	    int[] array = new int[num];

	    for (int n = 0; n < num; n++){
	      array[n] = sc.nextInt();
	    }
	    
	    for (int i = array.length - 1; i >= 0; i--){
	    	if (array[i] == num){
	    		num--;
	    	}
	    }
	    System.out.println(num);
	}
}