package main

import (
        "fmt"
)

func solution(h, w int, s [][]string) string {
        for i := 0; i < h; i++ {
                for j := 0; j < w; j++ {
                        if s[i][j] == "#" {
                                if i > 0 && s[i-1][j] == "#" {
                                        continue
                                }
                                if i < h-1 && s[i+1][j] == "#" {
                                        continue
                                }
                                if j > 0 && s[i][j-1] == "#" {
                                        continue
                                }
                                if j < w-1 && s[i][j+1] == "#" {
                                        continue
                                }
                                return "No"
                        }
                }
        }
        return "Yes"
}

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