def main():
    n, m = map(int, input().split())
    a = [int(input()) for _ in range(m)]
    a = set(a)

    s[0] = 1
    s[1] = 1 if 1 not in a else 0

    for i in range(2, n+1):
        if i in a:
            continue
        s[i] = (s[i-1] + s[i-2]) % 1000000007

    print(s[n])

main()