N, M = map(int, input().split())
A = [int(input()) for _ in range(M)]
q = 1000000007

if N == 1:
    if M == 0:
        print(1)
    elif M == 1:
        print(0)
else:
    cost = [0 for _ in range(N + 1)]
    cost[0] = 1
    if 1 in A:
        cost[1] = 0
    else:
        cost[1] = 1
    cost[2] = cost[0] + cost[1]

    cnt = 0
    A.append([0])
    for i in range(1, N + 1):
        if i == A[cnt]:
            cost[i] = 0
            cnt += 1
        else:
            cost[i] = (cost[i - 1] + cost[i - 2]) % q

    print(cost[-1])
