def resolve():
    n,m= map(int,input().split())
    a = [int(input()) for _ in range(m)]
    d = [0]*(n+1)
    if not 1 in a : d[1] = 1
    if not 2 in a : d[2] = d[1] + 1
    for i in range(3,n+1):
        if not i in a :
            d[i] += ( d[i-1] + d[i-2] ) % 1000000007
    print(d[i])

resolve()