import java.util.*

fun main(args: Array<String>) {
    val sc = Scanner(System.`in`)
    val h = sc.nextInt()
    val w = sc.nextInt()
    val t = (1..h).map { sc.next() }
    val dx = arrayOf(0, -1, 1, 0)
    val dy = arrayOf(-1, 0, 0, 1)
    for (i in 0 until h) {
        for (j in 0 until w) {
            if (t[i][j] == '.') {
                continue
            }
            var yes = false
            for (k in 0 until 4) {
                val nx = j + dx[k]
                val ny = i + dy[k]
                if (nx in 0 until w && ny in 0 until h && t[ny][nx] == '#') {
                    yes = true
                    break
                }
            }
            if (!yes) {
                println("No")
                return
            }
        }
    }
    println("Yes")
}