#include <bits/stdc++.h>
#define cin in
#define cout out
#define NMAX 1000006
using namespace std;

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

int fi[NMAX];

int main()
{
    int n;
    cin>>n;
    for(int i=1; i<=n; i++)
        fi[i]=i;
    for(int i=2; i<NMAX; i++)
        if(fi[i]==i)
            for(int j=1; j<=n; j+=i)
                fi[j]= fi[j]/i* (i-1);
    long long s=0;
    for(int i=1; i<=n; i++)
        s+=fi[i];
    s= s*2+1;
    cout<<s;
}