fun main(args: Array<String>) {
    val (H, W) = readLine()!!.split(" ").map(String::toInt)
    // 入力を各セルごとの二次元リストに
    val cellsList: List<List<String>> = List(H) { readLine()!!.chunked(1) }
    // 行ごとに、黒色セルのインデックスのリストを取得
    val blackIndices = cellsList.map {
        it.mapIndexedNotNull { index, value ->
            if (value == "#") index else null
        }
    }

/*
    //Check Print
    cellsList.forEach { println(it) }
    blackIndices.forEach { println(it) }
*/

    for (vecY in (-H + 1)..(H - 1)) for (vecX in (-W + 1)..(W - 1)) {
        if (tryPaintB(cellsList, blackIndices, H, W, vecY, vecX)) {
            println("YES")
            return
        }
    }
    println("NO")
}

fun tryPaintB(
    cellsList: List<List<String>>,
    blackIndices: List<List<Int>>,
    H: Int,
    W: Int,
    vecY: Int,
    vecX: Int
): Boolean {

    //val cells = cellsList.map { it.toMutableList() }
    val rangeY =
        if (vecY < 0)
            ((H - 1) downTo 0).toList()
        else
            (0 until H).toList()

    val indices =
        if (vecX < 0)
            blackIndices.map { it.reversed().toMutableList() }
        else
            blackIndices.map { it.toMutableList() }

    var flg: Boolean? = null

/*
    //Check Print
    println("vec = $vecY, $vecX")
    println("Y_range = $rangeY")
    println("blackIndices =")
    indices.forEach { println(it) }
*/

    for (y in rangeY) {
        while (indices[y].isNotEmpty()) {
            var trgY = y
            var trgX = indices[y].first()

            while (rangeY.contains(trgY) && indices[trgY].contains(trgX)) {
                //cells[y][x] = "R"
                indices[trgY].removeAt(0)
                trgY += vecY
                trgX += vecX
                if (rangeY.contains(trgY) && indices[trgY].contains(trgX)) {
                    //cells[trgY][trgX] = "B"
                    indices[trgY].remove(trgX)
                    if (flg == null) flg = true
                    trgY += vecY
                    trgX += vecX
                } else {
                    //flg = false
                    return false
                }
            }
//            if (rangeY.contains(trgY) && indices[trgY].contains(trgX)) {
//                //cells[trgY][trgX] = "B"
//                indices[trgY].remove(trgX)
//                if (flg == null) flg = true
//            } else {
//                //flg = false
//                return false
//            }
        }
    }

/*
    //Check Print
    cells.forEach { println(it.joinToString("")) }
    println(flg)
    println(" ")
*/

    return flg ?: false
}