h, w = map(int, input().split())
mass = [list(input()) for _ in range(h)]

ans = "Yes"
for i in range(w):
    for j in range(h):
        if mass[i][j] == "#":
            if i < w-1:
                if mass[i+1][j] == "#":
                    continue
            if 0 < i:
                if mass[i-1][j] == "#":
                    continue
            if j < h-1:
                if mass[i][j+1] == "#":
                    continue
            if 0 < j:
                if mass[i][j-1] == "#":
                    continue
            ans = "No"
            break

print(ans)