#include <bits/stdc++.h>
#define MOD 666013
#define ull unsigned long long
using namespace std;

ifstream fin("fractii.in");
ofstream fout("fractii.out");

int v[1000003];

int main()
{
    int n,i,j;
    fin>>n;
    for(i = 1; i <= n; i++){
        v[i] = i-1;
    }
    for(i = 2; i <= n; i++){
        for(j = 2*i; j <= n; j+=i){
            v[j] = v[j] - v[i];
        }
    }
    ull sol = 1;
    for(i = 1; i <= n; i++){
        sol+=2*v[i];
    }
    fout<<sol<<endl;
    return 0;
}