n, m = map(int, input().split())
a = [int(input()) for _ in range(m)]
MOD = 10 ** 9 + 7
# ---------------------------
dp = [0] * (n + 1)
dp[0] = 1
if (1 in a):
    dp[1] = 0
else:
    dp[1] = 1
# dp approach

for i in range(2, n + 1):
    if (i in a):
        dp[i] = 0
    elif (dp[i - 1] == 0 and dp[i - 2] == 0):
        print(0)
        exit()
    else:
        dp[i] = dp[i - 1] + dp[i - 2]


print(dp[n] % MOD)
