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

public class Main {
	public static void main (String[] args) throws Exception {
	    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		HashSet<Integer> used = new HashSet<>();
		int count = 0;
		for (int i = 0; i < n; i++) {
		    int x = Integer.parseInt(br.readLine());
		    for (int j = 1; j < x; j++) {
		        if (!used.contains(j)) {
		            count++;
		        }
		    }
		    used.add(x);
		}
		System.out.println(count);
    }
}