H, W = map(int, input().split())
s = [[] for i in range(H)]
num = 0
judge = 0
start = []
for i in range(H):
    s[i] = input()
    if '#' in s[i]:
        start.append([i, s[i].index('#')])
        num += s[i].count('#')

if num == 0:
    print('Yes')
elif num == 1:
    print('No')
else:
    for nowy, nowx in start:
        flag = False
        for y, x in [1, 0], [-1, 0], [0, 1], [0, -1]:
            if 0 <= y+nowy <= H-1 and 0 <= x+nowx <= W-1:
                if s[nowy+y][nowx+x] == '#':
                    flag = True
        if flag == True:
            judge += 1
    if judge == num:
        print('Yes')
    else:
        print('No')