# coding: utf-8
# Your code here!

import sys

# while : 0
# black : 1
H, W = map(int, input().rstrip().split(' '))
field = [[0] * W for _ in range(H)]

for i in range(H):
    for j, c in enumerate(input()):
        if c == '#':
            field[i][j] = 1
          
if H == 1 and W == 1:
    if field[0][0] == 1:
        print('No')
    else:
        print('No')
    sys.exit()
            
for h in range(H):
    for w in range(W):
        if field[h][w] == 1:
            if h + 1 < H:
                if field[h + 1][w] == 1:
                    continue
            if h - 1 > 0:
                if field[h - 1][w] == 1:
                    continue
            if w + 1 < W:
                if field[h][w + 1] == 1:
                    continue
            if w - 1 > 0:
                if field[h][w - 1] == 1:
                    continue
                    
            print('No')
            sys.exit()
            
print('Yes')
        
            
