h, w = map(int, input().split())
masu = ['.'*(w+2)]
masu += ['.' + input() + '.' for _ in range(w)]
masu.append('.'*(w+2))
ans = 'Yes'
for i in range(1,h-1):
    for j in range(1,w-1):
        if masu[i][j] == '#':
            if masu[i+1][j] == '#' or masu[i-1][j] == '#' or masu[i][j+1] == '#' or masu[i][j-1] == '#':
                continue
            else:
                ans = 'No'
                break
print(ans)