# Typical Stairs
import sys
input = sys.stdin.readline
import numpy as np

def main():
    n, m = map(int, input().split())
    a = []
    a_ = a.append
    MOD = 10**9 + 7
    for i in range(m):
        a_(int(input()))

    if n == 1:
        print(1)
        exit()

    a = np.array(a)

    dp = [0 for _ in range(n+1)]
    dp[0] = 1
    dp = np.array(dp)
    if 1 in a:
        dp[1] = 0
    else:
        dp[1] = 1

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

    print(dp[-1])

if __name__ == '__main__':
    main()
