h,w = map(int, input().split())
s = [list(input()) for i in range(w)]
dx = [0,1,0,-1]
dy = [1,0,-1,0]

for x in range(h):
    for y in range(w):
        if s[x][y] == "#":
            flag = False

            for i in range(4):
                nx = x + dx[i]
                ny = y + dy[i]
                if 0 <= nx < h and 0 <= ny < w and s[nx][ny] == "#":
                    flag = True

            if not flag:
                print("No")
                exit()

print("Yes")