public class No_123 {

	public static void main(String[] args) {
		java.util.Scanner sc = new java.util.Scanner(System.in);
		int n = sc.nextInt();
		int card[] = new int[n];

		for (int i = 1; i <= n; i++) {
			card[i - 1] = i;
		}

		int m = sc.nextInt();
		int[] shuffle = new int[m];
		for (int i = 0; i < m; i++) {
			shuffle[i] = sc.nextInt();
		}

		for (int s : shuffle) {
			int tmp = card[s - 1];// 抜くカードを確保
			for (int i = s - 1; i > 0; i--) {
				card[i] = card[i - 1];// 後ろにコピーしてゆく
			}
			card[0] = tmp;// 抜いたカードを一番上に積む
		}
		System.out.println(card[0]);
		sc.close();

	}

}