N, M = map(int, input().split())
mod = 1000000007
dp = [0] * (N+2)
A = [int(input()) for _ in range(M)] 
dp[-2] = 1

for i in range(N-1, -1, -1):
    if (i in A) == False:
        dp[i] = (dp[i + 1] + dp[i + 2]) % mod 

print(dp[0])