// n queens problem
class Queen{
    List<Move> list = new ArrayList<>();
    private int width = 4;
    public Queen(int width){
        this.width = width;
    }

    class Move{
        public int c;
        public int r;
        public Move(int c, int r){
            this.c = c;
            this.r = r;
        }
    }

    // int c = 0;
    public void queenSolver(int c){
        if(c == width){
            for(Move m:list){
                Print.p("[" + m.c + "," + m.r + "]");
            }
            Ut.l();
        }else{
            for(int r=0; r<width; r++){
                if(isValidMove(c, r)){
                    list.add(new Move(c, r));
                    queenSolver(c+1);
                    list.remove(list.size()-1);
                }
            }
        }
    }
    public boolean isValidMove(int c, int r){
        for(Move m : list){
            if(m.r == r || Math.abs(m.c - c) == Math.abs(m.r - r))
                return false;
        }
        return true;
    }
}