H,W = map(int,input().split())
G = [str(input()) for _ in range(H)]

def search(x,y):
    flag = 0
    if x > 0:
        if G[y][x-1] == "#":
            flag = 1
    if x < W-1:
        if G[y][x+1] == "#":
            flag = 1
    if y > 0:
        if G[y-1][x] == "#":
            flag = 1
    if y < H-1:
        if G[y+1][x] == "#":
            flag = 1
    if flag == 1:
        return True
    else:
        return False

res = 1
for i in range(H):
    for j in range(W):
        x = j
        y = i
        if G[i][j] == "#":
            if search(x,y):
                res = 1
            else:
                res = 0
                break
    else:
        break
if res:
    print("Yes")
else:
    print("No")