h, w = map(int, input().split())
cells = []
cells.append(['0']*(w+2))
for i in range(h):
    l = [0]
    s = input().split()
    l+=list(s[0])
    l+=[0]
    cells.append(l)
cells.append([0]*(w+2))

is_ok = True
for i in range(1,len(cells)-1):
    for j in range(1,len(cells)-1):
        if cells[i][j] == '#':
            if cells[i-1][j] == '#':
                is_ok = True
            elif cells[i+1][j] == '#':
                is_ok = True
            elif cells[i][j-1] == '#':
                is_ok = True
            elif cells[i][j+1] == '#':
                is_ok = True
            else:
                is_ok = False
        if not is_ok:
            print("No")
            exit()
print("Yes")