N, M = map(int, input().split())
a = set([int(input()) for i in range(M)])
n = [0] * N
n[0] = 1
n[1] = 2

#listの中をinで探すのはくっそ遅い
if N == 1:
    print(1)
    exit()
if 1 in a and 2 in a:
    print(0)
    exit()
if 1 in a:
    n[0] = 0
    n[1] = 1
if 2 in a:
    n[1] = 0

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

print(n[N - 1])