//http://www.infoarena.ro/problema/fractii

#include <iostream>
#include <fstream>
using namespace std;
int v[1000000];

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