#include <bits/stdc++.h>
using namespace std;

#define ll long long

int gcd_sum(int n)
{
    ll sum = 0;
    for(int i = 1; i <= n; i++)
        sum += __gcd(i,n); // built in function to calculate GCD
    return sum;
}

int main()
{
    ll n;
    cin >> n;
    cout << gcd_sum(n) << endl;

    return 0;
}