#include <iostream>
#include <fstream>
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
int n,i,j,v[1000001];
long long s=0;
int main()
{
    in>>n;
    for(i=1;i<=n;i++)
        v[i]=i-1;
    for(i=2;i<=n;i++)           //ciurul lui Erathosten
        for(j=i*2;j<=n;j+=i)
        v[j]=v[j]-v[i];
    for(i=1;i<=n;i++)
        s+=v[i];
    out<<s*2+1;
}