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