public class EightQueens {

	static int [] rowNumbers = new int[8]; // ith entry in state, from 0 to howManyPlaced-1, indicates the row number of the rook in column i
	static int curColumn = 0;
	
	private static boolean canBePlaced(int row) {
		for (int col = 0; col<curColumn; col++) 
			if (rowNumbers[col]==row || Math.abs(rowNumbers[col]-row) == curColumn-col)
				return false;
		return true;
	}
	
	private static int howManyWays() {
		System.out.println(curColumn);

		if (curColumn==8)
			return 1;
		int total = 0;
		for (int row=0; row<8; row++) {
			if (canBePlaced(row)) {
				rowNumbers[curColumn]=row;
				curColumn++;
				total+=howManyWays();
				curColumn--;
			}
		}
		
		return total;				
	}
	
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		System.out.println(howManyWays());

	}

}