MOD = 10**9 + 7
N, M = map(int, input().split())
A = [int(input()) for _ in range(M)]
dp = [0] * (N+1)
dp[0] = 1
for i in range(1, N+1):
    if i in A:
        dp[i] = 0
        continue
    dp[i] = dp[i - 1]
    if i > 1:
        dp[i] = dp[i - 1] + dp[i - 2]
# print(dp)
print(dp[N] % MOD)