#include <bits/stdc++.h>

using namespace std;

ifstream f("fractii.in");
ofstream g("fractii.out");

int v[1000002],n;
long long sum;
bool neprim[1000002];

int main()
{
    f>>n;
    for (int i=2;i<=n;++i)
    {
        v[i]=i;
    }
    for (int i=2;i<=n;++i)
    {
        if (!neprim[i])
        for (int j=i;j<=n; j+=i)
        {
            neprim[j]=true;
            v[j]-= v[j]/i;
        }
        sum+=v[i];
    }
    g<<'\n'<<2*sum+1;
    return 0;
}