h, w = input().split()
h = int(h)
w = int(w)
field = []
for _ in range(h):
    field.append(input())
    
ans = True
for i in range(h):
    for j in range(w):
        if field[i][j] == '#':
            temp = 1
            dd = [(1, 0), (-1, 0), (0, 1), (0, -1)]
            for ddd in dd:
                dx, dy = ddd
                nx, ny = x + dx, y + dy
                if nx >= 0 and nx < h and ny >= 0 and ny < w and field[nx][ny] == '#':
                    temp += 1
            if temp == 1:
                ans = False
                break

if ans:
    print("Yes")
else:
    print("No")