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