from collections import deque

def main():
    N, M = map(int, input().split())
    A = tuple(map(int, input().split()))

    card = deque(range(1, N + 1))
    for i in A:
        i -= 1
        card.appendleft(card[i])
        card.remove(card[i])

    print(card[0])

main()