N, M = map(int, input().split())
A = list(map(int, input().split()))
cards = [i for i in range(1, N + 1)]

for a in A:
    a -= 1
    memo = cards[a]
    for i in range(a - 1, -1, -1):
        # A[i] を A[i +1] にうつす
        cards[i + 1] = cards[i]
    cards[0] = memo

print(cards[0])