int n = in.nextInt();
int k = n/3;

if(n == 1){
    System.out.println(1);
}
else if(n%3 == 0){
    System.out.println(k*k*k);
}
else if(n%3 == 1){
    System.out.println((k+1)*k*k);
}
else if(n%3 == 2){
    System.out.println((k+1)*(k+1)*k);
}