n,m=map(int,input().split())
a=[int(input()) for _ in range(m)]
dp=[0 for _ in range(n+1)]
dp[0]=1
for i in range(1,n+1):
    if i in a:
        dp[i]=0
    else:
        dp[i]=(dp[i-1]+dp[i-2])%1000000007
print(dp[-1])