#include<iostream>
#include<fstream>
#include<stdio.h>
using namespace std;
long long phi[1000005];
int main()
{long long i,j,n,suma=0;
    ifstream fin("fractii.in");
    fin>>n;
    for(i=1;i<=n;i++)
      phi[i]=i-1;
    for(i=2;i<=n;i++)
        for(j=2*i;j<=n;j+=i)
        phi[j]-=phi[i];
     for(i=1;i<=n;i++)
     suma+=phi[i];

     fin.close();
     freopen("fractii.out","w",stdout);
     printf("%lld \n",suma*2+1);
     return 0;

}