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

dx = [0, 1, 0, -1]
dy = [1, 0, -1, 0]
for h in range(H):
    for w in range(W):
        if S[h][w] == '#' or 'b':
            for i in range(4):
                nh, nw = h+dx[i], w+dy[i]
                if 0 <= nh < H and 0 <= nw < W:
                    if S[nh][nw] == '#' or S[nh][nw] == 'b':
                        S[nh][nw] = 'b'
                        S[h][w] = 'b'

counter = 0
for i in range(H):
    for l in range(W):
        if S[i][l] == "#":
            counter += 1


if counter == 0:
    print("Yes")
else:
    print("No")
