H, W = map(int,input().split())
s = [list(input()) for i in range(H)]
ans = "Yes"
ushm = [[-1, 1, 0, 0],[0, 0, -1, 0]]
for i in range(H):
    for j in range(W):
        tmp = 0
        if s[i][j] == "#":
            if i > 0:
                if s[i-1][j] == "#":
                    tmp = 1
            if i < H - 1:
                if s[i+1][j] == "#":
                    tmp = 1
            if j > 0:
                if s[i][j-1] == "#":
                    tmp = 1
            if j < W - 1:
                if s[i][j+1] == "#":
                    tmp = 1
            if tmp == 0:
                ans ="No"
                break
    if tmp == 0:
        break
print(ans)