def main():
    N, M = map(int, input().split())
    cards = [card for card in range(1, N + 1)]
    #print(cards)
    for num in list(map(int, input().split())):
        digit = cards.pop(num - 1)
        cards.insert(0, digit)

    print(cards[0])


if __name__ == '__main__':
    main()