H, W=map (int, input().split(' '))
z=[]

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

#上下左右なので斜めは消す
dx = [ 0,  -1,  1,   0, ]
dy = [ 1,   0,  0,  -1, ]

for h in range(H):
    for w in range(W):
        if z[h][w] == '#': 
            p=0
            for i in range(4):
                x = w + dx[i]
                y = h + dy[i]

                if x < 0 or y <0 or x > W-1 or y >H-1:
                    continue

                print("x:"+str(x)+" y:"+str(y))
                if z[y][x]=="#":
                    p+=1
            if p==0:
                print('No')
                exit()

print('Yes')
                