h,w=map(int,input().split()) 
l = [input() for _ in range(h)]
dx = [1,-1,0,0]
dy = [0,0,1,-1]
ans = 'ans'
for i in range(h):
    for j in range(w):
        if l[i][j] =='#':
            for di in range(4):
                y = i+dx[di]
                x = j+dy[di]
                if x<0 or y<0 or x>w-1 or y>h-1:
                    continue
                else:
                    if l[y][x] !='#':
                        ans = 'No'
print(ans)