h,w=map(int,input().split())
grid=[list(input())  for i in range(h)]

dx=[-1,0,1,0]
dy=[0,1,0,-1]
for i in range(h):
    for j in range(w):
        if grid[i][j]=='#':
            flag=False
            for k in range(4):
                x=i+dx[k]
                y=j+dy[k]
                if 0<=x<w and 0<=y<h and grid[x][y]=='#':
                    flag=True
                    break
            if flag:
                continue
            else:
                print('No')
                exit()
print('Yes')