#!/usr/bin/env python3

import math

h,w = list(map(int,input().split(" ")))

c = []

for i in range(h):
    l = list(input())
    c.append(l)

for i in range(h):
    for j in range(w):
        if c[i][j] == "#":
            if j != 0:
                if c[i][j-1] == "#":
                    break
            if j != w-1:
                if c[i][j+1] == "#":
                    break
            if i != 0:
                if c[i-1][j] == "#":
                    break
            if i != h-1:
                if c[i+1][j] == "#":
                    break
            else:
                print('No')
                exit()
print('Yes')