N, M = map(int, input().split())
a = [int(input())for i in range(M)]
MOD = 10 ** 9 + 7
dp = [0] * (N + 1)

dp[0] = 0
dp[1] = 1 if 1 not in a else 0
dp[2] = 1 if 2 not in a else 0
for i in range(3, N + 1):
    if i in a:
        dp[i] = 0
    else:
        dp[i] = dp[i - 1] + dp[i - 2]

print(dp[N] % MOD)
