import numpy as np


def main(n, m, a):
    dp = np.zeros(n + 1)
    dp[0] = 1
    dp[1] = 1 if 1 not in a else 0

    for i in range(2, len(dp)):
        dp[i] = dp[i - 1] + dp[i - 2] if i not in a else 0
        dp[i] %= 1000000007

    return dp[-1]


if __name__ == '__main__':
    N, M = map(int, input().split())
    A = set()
    for _ in range(M):
        A.add(int(input()))

    print(main(N, M, A))
