H,W = map(int,input().split())
L = []
for i in range(H) :
    L.append(list(input()))

dxy = [(1,0),(-1,0),(0,1),(0,-1)]

flag = 0
for x in range(W) :
    for y in range(H) :
        if L[x][y] == "#" :
            for dx,dy in dxy :
                nx = x+dx
                ny = y+dy
                if (0 <= nx <= W-1) and (0 <= ny <= H-1) :
                    if L[nx][ny] == "#" :
                        flag = 0
                        
                        break
                    flag = 1
                else :
                    continue

if flag != 1 :
    print("Yes")
else :
    print("No")
    