#include <fstream>
#include <iostream>

#define Nmax 1000111

using namespace std;

int v[Nmax];

long long int n,s=0,rasp;

int main()
{
    ifstream fin ("fractii.in");
    ofstream fout ("fractii.out");
    fin>>n;
    for (int i=1;i<=n;++i)
    {
        v[i]=i-1;
    }
    for (int i=1;i<=n;++i)
    {
        for (int j=2*i;j<=n;j+=i)
        {
            v[j]-=v[i];
        }
    }
    for (int i=1;i<=n;++i)
    {
        s+=v[i];
    }
    s=s*2+1;
    fout<<s;
}