package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func out(x ...interface{}) {
	fmt.Println(x...)
}

var sc = bufio.NewScanner(os.Stdin)

func getInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func getString() string {
	sc.Scan()
	return sc.Text()
}

func main() {
	sc.Split(bufio.ScanWords)

	H, W := getInt(), getInt()
	s := make([]string, H)

	for i := 0; i < H; i++ {
		s[i] = getString()
	}

	ans := "Yes"
L:
	for y := 0; y < H; y++ {
		for x := 0; x < H; x++ {
			if s[y][x] == '#' {
				flg := 0
				if x != 0 {
					if s[y][x-1] == '#' {
						flg = 1
					}
				}
				if x != W-1 {
					if s[y][x+1] == '#' {
						flg = 1
					}
				}
				if y != 0 {
					if s[y-1][x] == '#' {
						flg = 1
					}
				}
				if y != H-1 {
					if s[y+1][x] == '#' {
						flg = 1
					}

				}
				if flg == 0 {
					ans = "No"
					break L
				}
			}
		}
	}
	out(ans)
}
