N, M = map(int, input().split())
a = [int(input()) for _ in range(M)]
MOD = 10 ** 9 + 7
dp = [0] * (N + 1)
dp[0] = 1
for i in range(1, N + 1):
    if i in a:
        dp[i] = -1
        continue
    if i == 1:
        if not i - 1 in a:
            dp[i] = 1
    else:    
        if dp[i - 1] != -1:
            dp[i] += dp[i - 1] % MOD
        if dp[i - 2] != -1:
            dp[i] += dp[i - 2] % MOD
print(dp[-1] % MOD)