using System;
using System.Linq;
public class Hello{
    public static void Main(){
        
            int n=int.Parse(Console.ReadLine());
            var blocks = Console.ReadLine().Split().Select(int.Parse).ToArray();
            
            int x=n;
            int c=0;
            
            for(int i=blocks.Length-1;i>=0;i--)
            {
                if(blocks[i]==x)
                {
                    x--;
                    c++;        
                }    
            }
            
            Console.WriteLine(n-c);
        
    }
}