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