private static int CalculatePeacefulArrangement(int queenCount, int[] chessTable, int startPosition, int result)
    {
        if (startPosition == chessTable.Length)
        {
            result++;
            return result;
        }
        for (int i = 0; i < queenCount; i++)
        {
            var index = Array.IndexOf(chessTable, 0, startPosition + i, queenCount - i);
            if (index != -1)
            {
                var row = index - startPosition;
                NoteBeatenCellAscendingDiagonal(queenCount, chessTable, index, 1);
                NoteBeatenCellDiscendingDiagonal(queenCount, chessTable, index, 1);
                NoteBeatenCellHorizontal(queenCount, chessTable, index, row, 1);
                result = CalculatePeacefulArrangement(queenCount, chessTable, startPosition + queenCount, result);
                NoteBeatenCellAscendingDiagonal(queenCount, chessTable, index, -1);
                NoteBeatenCellDiscendingDiagonal(queenCount, chessTable, index, -1);
                NoteBeatenCellHorizontal(queenCount, chessTable, index, row, -1);
                i = row;
            }
            else break;
        }
        return result;
    }

    private static void NoteBeatenCellHorizontal(int queenCount, int[] chessTable, int index, int row, int marking)
    {
        var column = index / queenCount;
        for (int i = column; i < queenCount; i++)
        {
            chessTable[i * queenCount + row] += marking;
        }
    }
    private static void NoteBeatenCellAscendingDiagonal(int queenCount, int[] chessTable, int index, int marking)
    {
        for (int i = index; i < chessTable.Length; i += queenCount + 1)
        {
            chessTable[i] += marking;
            if (i / queenCount == queenCount - 1 || i % queenCount == queenCount - 1) break;
        }
    }
    private static void NoteBeatenCellDiscendingDiagonal(int queenCount, int[] chessTable, int index, int marking)
    {
        for (int i = index; i < chessTable.Length; i += queenCount - 1)
        {
            chessTable[i] += marking;
            if (i / queenCount == queenCount - 1 || i % queenCount == 0) break;
        }
    }

void PrintA()
{
    for (int i = 0; i < 100; i++) Console.WriteLine($"A {i}");
}

void PrintB()
{
    for (int i = 0; i < 100; i++) Console.WriteLine($"B {i}");
}

var taskA = Task.Run(()=>PrintA());
var taskB = Task.Run(()=>PrintB());

Task.WaitAll(taskA, taskB);