n,m=map(int, input().split())
a=[int(input()) for i in range(m)]

dp=['inf']*(n+1)
for i in range(m):
    dp[a[i]]=0
dp[0]=1
dp[1]=1
for i in range(2,n+1):
    if dp[i]==0:
        if dp[i+1]==0:
            print(0)
            exit()
        else:
            pass
    else:
        dp[i]=dp[i-1]+dp[i-2]
print(dp[n]%(10**9+7))
    
  
 