def abc096_c():
    import numpy as np
    h, w = map(int, input().split())
    c = np.zeros([h + 2, w + 2], dtype=int)
    for i in range(h):
        row = "." + input() + "."
        for j in range(w + 2):
            c[i + 1][j] = [0, 1][row[j] == "#"]

    for i in range(1, h + 1):
        for j in range(i, w + 2):
            if c[i][j] == 1 and np.sum(c[i][j] * [c[i - 1][j], c[i + 1][j], c[i][j - 1], c[i][j + 1]]) == 0:
                return "No"
            else:
                return "Yes"


print(abc096_c())