H,W = [int(i) for i in input().split()]
li = ['0'] * H
for i in range(H) :
    li[i] = list(input())
dx = [1,0,-1,0]
dy = [0,1,0,-1]
counta = 0
count = 0
for i in range(H) :
    for j in range(W) :
        if li[i][j] == "#" :
            counta+=1
for i in range(H) :
    for j in range(W) :
        if li[i][j] == "#" :
            for k in range(4) :
                nx = i + dx[k]
                ny = j + dy[k]
                if nx < 0 or nx > W-1 or ny < 0 or ny > H-1 :
                    continue
                if li[nx][ny] == "#" :
                    count+=1
                    break
if count == counta:
    print("Yes")
else:
    print("No")