n, m = map(int, input().split())
a = [int(input()) for _ in range(m)]
dp = [0] * (n + 1)
for i in range(m):
    dp[a[i]] = -1
mod = 10 ** 9 + 7
dp[0] = 1
dp[1] = 1
for i in range(2, n + 1):
    if dp[i] == -1:
        continue
    if dp[i - 1] == -1:
        dp[i] = dp[i - 2] % mod
    elif dp[i - 2] == -1:
        dp[i] = dp[i - 1] % mod
    #dp[i] = max(dp[i - 1], dp[i - 2])
    else:
        dp[i] = (dp[i - 1] % mod + dp[i - 2] % mod) % mod
    #dp[i] %= mod
#dp[n]
if dp[n] == -1:
    print(0)
else:
    print(dp[n])