fun main(args: Array<String>){
    val (N, M) = readLine()!!.split(" ").map { it.toInt() }
    val A = IntArray(M){ readLine()!!.toInt() }
    val mod = 1_000_000_007L

    val dp = LongArray(N+1)
    dp[0] = 1
    if(!A.contains(1)){
        dp[1] = 1
    }
    A.forEach {
        dp[it] = -1L
    }
    for(i in 2..N){
        if(dp[i] != -1L){
            dp[i] = (if(dp[i - 1] != -1L) dp[i - 1] else 0) + (if(dp[i - 2] != -1L) dp[i - 2] else 0)
            dp[i] = dp[i] % mod
        }
    }
    println(dp[N])
}