
MOD = 10_0000_0007

def main():
    n,m = map(int,input().split())
    al = [False for _ in range(n+1)]
    for i in range(m):
        a = int(input())
        al[a] = True
    
    dp = [0 for _ in range(n+1)]
    dp[0] = 1
    dp[1] = 1 if al[1] == False else 0

    for i in range(2,n+1):
        if not al[i]:
            dp[i] = dp[i-2] + dp[i-1]

    print(dp[n] % MOD)


if __name__ == "__main__":
    main()