h, w = map(int, input().split())

s = [list(input()) for _ in range(h)]

DX = [-1, 0, 1, 0]
DY = [0, -1, 0, 1]

ans = True

for i in range(h):
    for j in range(w):
        flag = False
        for k in range(4):    
            if not(0<=i+DX[k]<=w-1 and 0<=j+DY[k]<=h-1):
                continue
            if s[i + DX[k]][j + DY[k]] == "#":
                flag = True
        ans = flag
print("Yes" if ans else "No")
