#include <iostream>
#include <fstream>
#define MAX 1000010

using namespace std;
typedef long long ll;

int n;
ll ans;
int a[MAX];

int main()
{
    ifstream f ("fractii.in");
    ofstream g ("fractii.out");
    f>>n;
    for(int i=1;i<=n;i++)a[i]=i;
    for(int i=1;i<=n;i++){
      ans+=(ll)a[i];
      for(int j=i*2;j<=n;j+=i) a[j]-=a[i];
    }
    g<<ans*2LL-1;
    f.close ();
    g.close ();
    return 0;
}