n,m = map(int, input().split())
a = [int(input()) for _ in range(m)]
mod = 10**9+7
dp = [0]*(n+1)
dp[0] = 1
dp[1] = 0 if 1 in a else 1
for i in range(2, n+1):
    dp[i] = (dp[i-1]+dp[i-2])%mod if i not in a else 0 #かけたところは0にしとこう、ってことか…
print(dp[n])