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

dp = [0] * (N + 1)
dp[0] = 1
dp[1] = 0 if 1 in lst_a else 1
for i in range(2, N+1):
    dp[i] = 0 if i in lst_a else dp[i-1] + dp[i-2]
ans = dp[N] % MOD

print(ans)