H, W = map(int, input().split())
grid = []
for i in range(0,H):
    grid.append(list(input().split()))
ans = "Yes"
for i in range(0,H):
    line = grid[i][0].split(".")
    if "#" in line:
        index = line.index("#")
        if i == 0 or i == H-1:
            continue
        previous = grid[i-1]
        next = grid[i+1]
        if next[0][index] == "." and previous[0][index] == ".":
            ans = "No"
            break
print(ans)