import sys
import os

MOD = 10 ** 9 + 7


def main():
    if os.getenv("LOCAL"):
        sys.stdin = open("input.txt", "r")

    N, M = list(map(int, sys.stdin.buffer.readline().split()))
    A = [int(sys.stdin.buffer.readline().rstrip()) for _ in range(M)]

    ret = [0, 1]
    for i in range(1, N + 1):
        if i in A:
            ret.append(0)
        else:
            ret.append((ret[-1] + ret[-2]) % MOD)

    print(ret[-1] % MOD)


if __name__ == '__main__':
    main()
