import sys
import copy
import math
import itertools
import numpy as np

H,W = [int(c) for c in input().split()]
s = [list(input()) for c in range(H)]
a = [[1 for c in range(W)] for d in range(H)]
b = [[0 for c in range(W)] for d in range(H)]

if H == 1 and W == 1:
    print("Yes")
    sys.exit(0)

for i in range(H):
    for j in range(W):
        if s[i][j]=="#":
            if i-1 > 0:
                if s[i-1][j] == "#":
                    a[i][j]=0
            if j-1 > 0:
                if s[i][j-1] == "#":
                    a[i][j]=0
            if j+1 < W:
                if s[i][j+1] == "#":
                    a[i][j]=0
            if i+1 < H:
                if s[i+1][j] == "#":
                    a[i][j]=0
        else:
            a[i][j]=0
        if a[i][j] == 1:
            print("No")
            sys.exit(0)

print("Yes")