import java.util.*;

class JengaSortFix3 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int length = sc.nextInt();
		int cnt = length - 1;
		HashSet<Integer> nset = new HashSet<Integer>();
		int maxInSet = sc.nextInt();
		nset.add(maxInSet);
		for (int i = 0; i < length - 1; i++) {
			int next = sc.nextInt();
			if (next > maxInSet) {
				maxInSet = next;
				if (nset.contains(next - 1)) {
					cnt--;
				} else {
					cnt = length - 1;
				}
			nset.add(next);
			}
		}
		System.out.println(cnt);
	}
}