def main():
    N, M = map(int, input().split())
    a = {int(input()): 1 for _ in range(M)}
    dp = [0] * (N + 1)
    dp[0] = 1
    if 1 not in a:
        dp[1] = 1

    for i in range(2, N + 1):
        if a[i]:
            dp[i] = 0
        else:
            dp[i] += dp[i-1] + d[i-2]
            dp[i] %= 1000000007

    print(dp[N])

main()
