#include <iostream>
#include <fstream>
using namespace std;

 ifstream f("fractii.in");
 ofstream g("fractii.out");
int v[1000005];
int main()
{int i,j;
    long long nr=0;
    int n;
    f>>n;

    for(i=1;i<=n;i++)
        v[i]=i-1;

    for(i=1;i<=n-1;i++)
        for(j=i+1;j<=n;j++)
            v[j]-=v[i];

    for(i=1;i<=n;i++)
        nr+=v[i];

    g <<nr*2+1;

}