#include<iostream>
#include<fstream>
#include<vector>
using namespace std;
int main ()
{
    ifstream x("fractii.in");
    ofstream y("fractii.out");
    long n,i,j;
    unsigned long long s=0;
    x>>n;
    vector<int>phi(n+1);
    for(i=1;i<=n;++i)
    phi[i]=i-1;
    for(i=2;i<=n;++i)
    for(j=2*i;j<=n;j+=i)
    phi[j]-=phi[i];
    for(i=2;i<=n;i++)
    s+=phi[i];
    y<<s*2+1;
    x.close();
    y.close();
    return 0;
}