#include <conio.h>
#include <stdio.h>
#include <iostream.h>
#include <math.h>

void main(){
	int n,k;
	cout<<"Dati n : ";
	cin>>n;
	double suma=0;

	for (k=1;k<=n;k++){
		double putere;
		putere=pow((double)-1,(double)n-k);
		double putk;
		putk=pow((double)k,(double)2);


		suma=suma+putk*putere;

	}
	cout<<suma<<endl;
	getch();
}