import java.io.*;
import java.lang.*;

class Monsters {
	static BufferedReader in;
	public static void main(String[] args) throws IOException{
		in = new BufferedReader(new InputStreamReader(System.in));

		String line;
		String[] pole;
		boolean vyh= true;

		while((line = in.readLine())!=null){
			int pocet = 0;
			int n = Integer.parseInt(line);

			line = in.readLine();
			pole = line.split(" ");
					
			for(int i = 0; i<n; i++){
				if(Integer.valueOf(pole[i])!=i+1) vyh = false;
			}
			if(!vyh){
			for(int i = n-1; i>0; i--){
				if(Integer.valueOf(pole[i])!=i+1){
					for(int y = 0; y<n;y++){
						if(i+1 == Integer.valueOf(pole[y])){
							pocet++;
							String temp = pole[i];
							pole[i] = String.valueOf(i+1);
							pole[y] = temp;
							break;
						}
					}				
				}
			}
			}
			System.out.println(pocet);
		}
	}
}