fun gridChallenge(grid: Array<String>): String
{
    val sorted_grid = grid.map { it.toCharArray().sorted() }
    
    for (i in 0..<grid.first().length)
    {
        val col_list = sorted_grid.map { it.get(i) }
        if (col_list != col_list.sortedBy { it }) return "NO"
    }
    
    return "YES"
}