N, M = map(int, input().split())
A = [int(input()) for _ in range(M)]


MOD = 1000000007

dp = [0 for _ in range(N + 1)]

dp[0] = 1



next_ng_index = 0

for index in range(N):
    current = index + 1
    if current == A[next_ng_index]:
        next_ng_index += 1
        if next_ng_index == M:
            next_ng_index = 0
        continue

    pre_stair = current - 1
    dp[current] += dp[pre_stair]

    prepre_stair = current -2
    if prepre_stair >= 0:
        dp[current] += dp[prepre_stair]

    dp[current] %= MOD

print(dp[-1]%MOD)





