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

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

print(dp[N-1] % MOD)
