#include<iostream>
#include<fstream>

using namespace std;

int a[1000001];

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