#include <iostream>
#include <fstream>
#define mil 1000000
using namespace std;

ifstream in("fractii.in");
ofstream out("fractii.out");
int n,phi[mil];

void build_phi()
{
    int i,j;
    phi[1]=1;
    for(i=2;i<=n;i++)
        phi[i]=i;

    for(i=2;i<=n;i++)
        if(phi[i]==i)
            for(j=i;j<=n;j+=i)
                phi[j]=phi[j]*((float)(i-1)/i);
}


int main()
{
    int i;
    long long sol=0;
    in>>n;

    build_phi();

    for(i=2;i<=n;i++)
        sol+=phi[i];
    sol=sol*2+1;
    out<<sol;
    return 0;
}