import sys
h, w = map(int, input().split())
s = [input() for _ in range(h)]
print(s)
dx = [0, 1, 0, -1]
dy = [1, 0, -1, 0]

for i in range(h):
    for j in range(w):
        if s[i][j] == '.':
            continue
        flag = 0
        for k in range(4):
            dh = i + dy[k]
            dw = j + dx[k]
            # print(dh, dw)
            if 0 <= dh < h and 0 <= dw < w and s[dh][dw] == '#':
                flag = 1
        if flag == 0:
            print('No')
            sys.exit()
print('Yes')
