#include <iostream>
#include <fstream>

using namespace std;

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

const int NMAX = 1000000;
int x[NMAX];

int main()
{
    int n;
    fin>>n;
    int i,j,nr,sum=0;
    x[1]=n;
    for(i=2;i<=n;i++)
    {
        if (x[i]==0)
        {
            nr=n/i-1;
            x[i]+=(n-(n/i));
            for(j=i*2;j<=n;j=j+i)
            {
                x[j]=x[j]-nr;
            }
        }
        else
        {
            x[i]+=n-1;
        }
        sum=sum+x[i];
    }
    fout<<sum+n;
    return 0;
}