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