def resolve():
    (N, M) = list(map(int, input().split(" ")))
    As = [int(input()) for i in range(M)]

    cnts = [False] * (N+1)
    for i in range(N+1):
        c = 0
        if i in As:
            c = 0
        elif i == 0:
            c = 1
        elif i == 1:
            c = 1
        elif i == 2:
            c = 2 if 1 not in As else 1
        else:
            c = (cnts[i-2] + cnts[i-1])%1000000007
        cnts[i] = c

    print(cnts[N])

if '__main__' == __name__:
    resolve()