h, w = map(int, input().split())
ls = [[_ for _ in input()] for _ in range(h)]

for i in range(h):
    ls[i] = ["."] + ls[i] + ["."]

ls_s = [["."] * len(ls[0])]
ls_s.extend(ls)
ls_s.extend([["."] * len(ls[0])])

for i in range(1, len(ls)+1):
    for j in range(1, len(ls)+1):
        if ls_s[i][j] == "#":
            if ls_s[i-1][j] == ls_s[i+1][j] == ls_s[i][j-1] == ls_s[i][j+1] == ".":
                print("No")
                break
        elif i == j == len(ls):
            print("Yes")
    else:
        continue
    break