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

for k in A:
    temp = listN[(k-1)]
    listN.remove(temp)
    listN.insert(0, temp)

print(listN[0])