//https://infoarena.ro/problema/fractii
#include <bits/stdc++.h>
using namespace std;

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

int d[1000010];
int main()
{
    int n,i,j;
    fin>>n;
    for(i=1;i<=n;i++)
    {
        d[i]=i;
    }
    for(i=1;i<=n;i++)
    {
        for(j=2*i;j<=n;j+=i)
        {
            d[j]-=d[i];
        }
    }
    long long rez=0;
    for(i=1;i<=n;i++)
    {
        //cout<<d[i]<<" ";
        rez+=d[i];
    }
    fout<<rez*2-1;

    return 0;
}