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

dp = [0] * (N+1)
dp[0] = 1
dp[1] = 1 if 1 not in a else 0

for i in range(2, N+1):
    if i in a:
        continue
    dp[i] += (dp[i-1] + dp[i-2]) % MOD
print(dp[N] % MOD)