#include<iostream>
#include<fstream>
#include<ctime>
using namespace std;
unsigned long long g(unsigned long long a,unsigned long long b) 
{
    if(a==0)
    {
        return b;
    }else
    {
        return g(b%a,a);
    }
}
int main()
{
	ifstream fin("gcdsum.in");
	ofstream fout("gcdsum.out");
	long long n;
	long long sum=0;
	fin>>n;
	for (int i=1;i<=n;i++)
		sum+=g(i,n);
	fout<<sum<<endl;
	fin.close();
	fout.close();
	return 0;
}