n, m = map(int, input().split())

aaa = [int(input()) for i in range(m)]

dp = [0] * (n + 1)
dp[0] = 1
dp[1] = 1 if 1 not in aaa else 0
MOD = 10 ** 9 + 7
 
for i in range(2, n + 1):
    if i in aaa:
        continue
    dp[i] = (dp[i - 2] + dp[i - 1]) % MOD
print(dp[n])