H,W = map(int,input().split())
L = [input() for i in range(H)]
dxy = [[1,0],[-1,0],[0,1],[0,-1]]

for y in range(H) :
    for x in range(W) :
        if L[y][x] == "#" :
            for dx,dy in dxy :
                nx = x+dx
                ny = y+dy
                if (0 <= nx <= W-1) and (0 <= ny <= H-1) :
                    if L[ny][nx] == "#" :
                        break
                    print("No")
                    exit()
print("Yes")
