N,M = map(int,input().split())
A = [int(input()) for i in range(M)]
MOD = 10**9+7



dp = [0]*(N+1)
dp[0] = 1
for i in range(N):
    if i+1 not in A:
        dp[i+1] += dp[i]
        dp[i+1] %= MOD
    if i+2 <= N and i+2 not in A:
        dp[i+2] += dp[i]
        dp[i+2] %= MOD
print(dp[-1]%MOD)
