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

grid = [[str(i) for i in input()]for _ in range(h)]
dxdy = [[1, 0], [0, 1], [-1, 0], [0, -1]]

for i in range(h):
    for j in range(w):
        if grid[i][j]=="#":
            f = False
            for d in dxdy:
                if(i+d[0]>-1 and j+d[1]>-1 and i+d[0]<w and j+d[1]<h):
                    if grid[i+d[0]][j+d[1]]=="#":
                        f = True
                        continue
            if f==False:
                print("No")
                exit()


print("Yes")
