big = 10**9 + 7

def typical_stairs(n,m,a):

    flag = [True]*(n+1)
    for i in range(m):
        tmp = a[i]
        flag[tmp] = False

    route = [0]*(n+1)
    route[0] = 1
    if flag[1]:
        route[1] = 1
    else:
        route[1] = 0

    for i in range(2,n+1):
        if flag[i]:
            route[i] = route[i-1] + route[i-2]

        ans = route[i]

    return ans%big
if __name__ == '__main__':
    n,m = map(int,raw_input().split())
    a = [int(raw_input()) for _ in range(m)]

    print typical_stairs(n,m,a)