import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int[] place = new int[n + 1];
        int[] values = new int[n + 1];
        for (int i = 1; i <= n; i++) {
            values[i] = sc.nextInt();
            place[values[i]] = i;
        }
        int count = 0;
        for (int i = 1; i <= n; i++) {
            while (values[i] > i) {
                int current = values[i];
                place[current] = place[current - 1];
                values[place[current - 1]] = current;
                values[i] = current - 1;
                place[current - 1] = i;
                count++;
            }
        }
        System.out.println(count);
    }
}
    
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}