h, w = map(int, input().split())
s = []
for _ in range(h):
    si = list(input())
    s.append(si[:-1])
flag = 1

for hi in range(h):
    for wi in range(w-1):
        black = 0
        if s[hi][wi] == '#':
            if hi > 0:
                if s[hi-1][wi] == '#':
                    black += 1
            if wi > 0:
                if s[hi][wi-1] == '#':
                    black += 1
            if hi < h-1:
                if s[hi+1][wi] == '#':
                    black += 1
            if wi < w-2:
                if s[hi][wi+1] == '#':
                    black += 1
            
            if black == 0:
                flag = 0
                break
    
    if flag == 0:
        break

if flag == 1:
    print('Yes')
else:
    print('No')