n,m = map(int,input().split())
li = [int(input()) for _ in range(m)]
mod = 10**9+7

dp = [1] + [0]*n

for i in range(1,n+1):
    if i in li:continue
    dp[i] = (dp[i-2] + dp[i-1])%mod
print(dp[-1]%mod)