H,W = input().split()
H,W = int(H),int(W)
nodes = [list(input()) for i in range(H)]


if H == 1 and W == 1 and nodes[0][0] == ".":
    print("No")
    quit()

for i in range(len(nodes)):
    for j in range(len(nodes)):
        if nodes[i][j] == "#":
            flag = False
            if i - 1 >= 0:
                if nodes[i-1][j] == "#":
                    flag = True
            if i + 1 < H:
                if nodes[i+1][j] == "#":
                    flag = True
            if j - 1 >= 0:
                if nodes[i][j-1] == "#":
                    flag = True
            if j + 1 < W:
                if nodes[i][j+1] == "#":
                    flag = True

            if flag == False:
                print("No")
                quit()

print("Yes")