N, M = list(map(int, input().split()))
A = list(map(int, input().split()))

list_N = list(range(N))

for a in A:
    tmp = []
    tmp.append(list_N[a-1])
    list_N.pop(a-1)
    tmp.extend(list_N)
    list_N = tmp

print(list_N[0] + 1)