import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[] r = new int[n - 1];
		for (int i = 0; i < n - 1; i++) {
			r[i] = sc.nextInt();
		}
		sc.close();

		int max = 1;
		int[] d = new int[n];
		for (int i = 0; i < n - 1; i++) {
			for (int j = max; j < r[i]; j++) {
				d[j] = d[i] + 1;
			}
			max = Math.max(max, r[i]);
		}
		System.out.println(d[n - 1]);
	}
}