using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

    static int GRID_SIZE = 8;

    public static bool checkValid(){

    }

    public static void placeQueens(int row, int[] columns, List<int[]> results){

        if(row == GRID_SIZE){ // Found valid placement

            results.Add(columns.Clone());

        }else{

            for(int col = 0; col < GRID_SIZE; col++){

                if(checkValid(columns, row, col){

                    columns[row] = col; // place queen

                    placeQueens(row + 1, columns, results);

                }

            }

        }

    }

}