n, m = list(map(int, input().split(' ')))
am = list(map(int, input().split(' ')))

deck = list(range(1, n + 1))

for a in am:
    v = deck[a - 1]
    for j in range(a - 1, 0, -1):
        deck[j] = deck[j - 1]
    deck[0] = v

print(deck[0])