#N,Wを入力
H,W = map(int, input().split())

trout = []

for i in range(H):
    trout.append(list(input()))

# 配列の比較用の変数
h = H-1
w = W-1

reslut = "Yes"
for i in range(H):
    for j in range(W):
        
        # "."だったらスルー
        if trout[i][j] == ".":
            pass
        
        else:
             # 真上
            if i>=1 and trout[i-1][j] == "#":
                pass
             # 左
            if j>=1 and trout[i][j-1] == "#":
                pass
            # 右
            if j<w and trout[i][j+1] == "#":
                pass
            # 真下
            if i<h and trout[i+1][j] == "#":
                pass
            
            else:
                reslut = "No"
                break
    else:
        continue
    break
    
print(reslut)