#include<fstream>
#include<vector>
using namespace std;int main(){long n,i,j;unsigned long long nr_fractii = 0LL;ifstream fin("fractii.in");fin>>n;fin.close();vector<long> sir(n+1,0);for(i = 2;i<=n;++i)sir[i]=i-1;for(i = 2;i<=n;++i){nr_fractii += sir[i];for(j=i+i;j<=n;j+=i)sir[j]=sir[j]-sir[i];}ofstream fout("fractii.out");fout<<nr_fractii*2+1;fout.close();return 0;}