import sys
input = sys.stdin.readline

MOD = 10 ** 9 + 7


def main():
    N, M = map(int, input().split())
    memo = [0] * (N + 1)
    a = [0] * M

    memo[0] = 0
    memo[1] = 1
    memo[2] = 2
    for i in range(3, N+1):
        memo[i] = memo[i-1] + memo[i-2]

    # print(memo)
    ans = 1

    for i in range(M):
        a[i] = int(input())

        if i != 0 and abs(a[i] - a[i-1]) == 1:
            print(0)
            return

        if a[i] == 1:
            ans *= 1
        elif i == 0:
            ans *= memo[a[i] - 1]
            ans %= MOD
            # print(a[i], ans, a[i] - 1)
        else:
            ans *= memo[a[i] - a[i-1] - 2]
            ans %= MOD
            # print(a[i], ans, a[i] - a[i-1] - 2)

    ans *= memo[N - a[M-1] - 1]
    ans %= MOD
    # print(ans, N - a[M-1] - 1)
    print(ans)


if __name__ == '__main__':
    main()
