package test8;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

/**
 * No.365 ジェンガソート
 * https://yukicoder.me/problems/no/365
 */

public class Question_24_0921 {

	final static int COUNT_MIN = 1;
	final static int LENTTH_MIN = 1;
	final static int COUNT_MAX = 100000;
	static int LENTTH_MAX;

	public static void main(String[] args) {
		InputStreamReader re = new InputStreamReader(System.in);
		BufferedReader br = new BufferedReader(re);

		try {
			int count = Integer.parseInt(br.readLine());
			LENTTH_MAX = count;
			String[] inputStr = br.readLine().split(" ");
			//int comparativeNum = Integer.parseInt(inputStr[0]);
			int resultCount = 0;
			int comparativeNum = count;
			boolean errorFlg = false;
			//ArrayList<Integer> list = new ArrayList<Integer>();
			//list.add(Integer.parseInt(inputStr[0]));

			//有効値判定
			if (NumJudg(count, COUNT_MIN, COUNT_MAX)) {
				for (int i = inputStr.length - 1; i > 0; i--) {
					int num = Integer.parseInt(inputStr[i]);
					if (NumJudg(num, LENTTH_MIN, LENTTH_MAX)) {
						if (num == comparativeNum) {
							comparativeNum--;
						} else {
							resultCount++;
						}
					} else {
						errorFlg = true;
						break;
					}
				}
				if (errorFlg) {
					System.out.println("入力値が有効範囲外です");
				} else {
					System.out.println(resultCount);
				}

			} else {
				System.out.println("入力値が有効範囲外です");
			}

		} catch (NumberFormatException e){
			System.out.println("数字を入力して下さい");
		} catch (IOException e) {
			System.out.println("エラーが発生しました");
		} finally {
			try {
				re.close();
				br.close();
			} catch (IOException e) {
				System.out.println("InputStreamReader、BufferedReaderクローズ中にエラーが発生しました");
			}
		}
	}

	/**
	 * 有効値判定
	 * @param input 判定するもの
	 * @param max 最大値
	 * @param min 最小値
	 * @return 範囲内ならtrue,範囲外ならfalseを返す
	 */
	private static boolean NumJudg(int input, int min, int max) {
		Boolean result = false;
		if (min <= input && input <= max) {
			result = true;
		}
		return result;
	}
}