h, w = map(int, input().split())
s = [['.']*(w+2)]
for _ in range(h):
    s.append(['.'] + list(input()) + ['.'])
s.append(['.']*(w+2))
ans = 'Yes'

for i in range(1, w):
    for j in range(1, h):
        if s[i][j] == '#':
            l = s[i][j-1]
            u = s[i-1][j]
            r = s[i][j+1]
            d = s[i+1][j]
            if l=='.' and u=='.' and r=='.' and d=='.':
                ans = 'No'

print(ans)