#include <iostream>

using namespace std;

int v[101];

int main()

{
    int val1=1;
    int val2=2;
    int N;
    cin >> N ;
    int S = 0;

    int nr =1 ;
    for(int i = 1; i <= N+1 ; ++i)
    {
        v[i] = nr;
        nr++;
    }
    for ( int i = 1 ; i <= N+1 ; ++i )
    {
        if( i % 2 != 0 )
        {
            S = S + v[val1] * v[val2];
            val1++;
            val2++;


        }

        else
        {
            S = S - v[val1] * v[val2];
            val1++;
            val2++;

        }
    }
cout <<"Rezultatul este" <<" "<< S;

}