n, m = map(int, input().split())
b = [False]*(n+1)
dp = [None]*(n+1)
M = 10**9+7
dp[0] = 1
dp[1] = 1

def up(x):
    if b[x] == True:
        return 0
    res = 0
    if dp[x-1] == None:
        dp[x-1] = up(x-1)
    res += dp[x-1]
    if dp[x-2] == None:
        dp[x-2] = up(x-2)
    res += dp[x-2]
    return (res%M)

for i in range(m):
    a = int(input())
    b[a] = True
if b[1] == True:
    dp[1] = 0
if n == 1:
    if b[1] == True:
        print(0)
    else:
        print(1)
    exit()
print(up(n))
