def resolve():
    # 整数 1 つ
    # n = int(input())
    # 整数複数個
    h, w = map(int, input().split())
    # 整数 N 個 (改行区切り)
    S = [list(input()) for i in range(h)]
    # 整数 N 個 (スペース区切り)
    # N = list(map(int, input().split()))
    # 整数 (縦 H 横 W の行列)
    # A = [list(map(int, input().split())) for i in range(H)]

    flag = True
    for i in range(h):
        for j in range(w):
            if S[i][j] == ".":
                continue
            else:
                if S[i][j-1] == "." and S[i][j+1] == "." and S[i-1][j] == "." and S[i+1][j] == ".":
                    flag = False
                    break
        if flag == False
            break

    if flag == False:
        print("No")
    else:
        print("Yes")


resolve()