w, h = list(map(int, input().split(' ')))

table = []
for w in range(h):
    row = input()
    table.append(row)


def is_paintable(r, c):
    if r > 0:
        if table[r-1][c] == "#":
            return True
    if r+1 < h:
        if table[r+1][c] == "#":
            return True
    if c > 0:
        if table[r][c-1] == "#":
            return True
    if c+1 < w:
        if table[r][c+1] == "#":
            return True
    else:
        return False

is_Yes = True
for i in range(h):
    if is_Yes == False:
        break
    for j in range(w):
        if table[i][j] == "#":
            if is_paintable(i, j) == False:
                print('No')
                is_Yes = False
                break
else:
    print('Yes')