package main

import (
	"fmt"
)

func grid(h, w int, input []string) string {
	dj := []int{0, 1, 0, -1}
	di := []int{1, 0, -1, 0}

	for i := range input {
		for j := range input[i] {
			if input[i][j] == '.' {
				continue
			}
			var valid bool
			for d := range dj {
				pi := i + di[d]
				pj := j + dj[d]
				if pi < 0 || w <= pi {
					continue
				}
				if pj < 0 || h <= pj {
					continue
				}
				if input[pi][pj] == '#' {
					valid = true
				}
			}
			if !valid {
				return "No"
			}
		}
	}
	return "Yes"
}

func main() {
	var h, w int
	fmt.Scan(&h, &w)
	input := make([]string, h)
	for i := range input {
		fmt.Scan(&input[i])
	}
	fmt.Println(grid(h, w, input))
}
