#カードシャッフル

line1 = input()
N = int(line1.split(" " )[0])
M = int(line1.split(" " )[1])

line2 = input()
a = line2.split(" " )

card = [1]
for i in range(2 , N+1):
    card.insert(len(card), i)

for i in a:
    c = card.pop(int(i) - 1)
    card.insert(0, c)

print(card[0])