static int row;

static int[] path;

static int count;

static int num = 15;

private static void findPath(){

for (int i =1; i <= num; i++){

if (detect(path, row, i)) continue;

row ++;

path[row - 1] = i;

if (row == num) {

//display (path);

count ++;

row --;

continue;

}

findPath();

row--;

}

path[row] = 0;

}

private static boolean detect(int[] x, int row, int target){

if (row == 0) return false;

for (int i = 1; i <= row; i++){

if (target == x[i-1] - (row - i +1) || target == x[i-1] + (row - i + 1)

|| target == x[i-1]){

return true;

}

}

return false;

}

private static void display (int[] x){

for (int i : x){

System.out.print(i + " ");

}

System.out.println("");

}

public static void main(String[] args) {

row = 0;

path = new int[num];

findPath();

System.out.println(count);

}