#129_C
n,m=map(int,input().split())
a=[int(input()) for _ in range(m)]
mod=10**9+7
dp=[1 for i in range(n+1)]
for i in range(1,n+1):
    if i in a:
        dp[i]=0
    elif i==1:
        dp[i]=dp[i-1]
    else:
        dp[i]=(dp[i-1]+dp[i-2])%mod
        
print(dp[n]%mod)