from collections import deque
n, m = map(int, input().split())
a = list(map(int, input().split()))
dq = deque([i for i in range(1, n + 1)])
for i in a:
    t = dq[i - 1]
    dq.remove(dq[i - 1])
    dq.appendleft(t)
print(dq.popleft())