#include <fstream>
#include <string.h>
using namespace std;
ofstream fout("fractii.out");
ifstream fin("fractii.in");
int suma,s,n,sumaux,frec[1000005];
long long nrmax;
int main()
{
    fin>>n;
    nrmax=n*n;
    for(int i=2;i<=n;i++)
    {
        memset(frec,0,sizeof(frec));
        int aux=i;
        int nr=2;
        while(aux!=1)
        {
            sumaux=0;
            if(aux%nr==0)
            {
                for(int j=nr;j<=n;j+=nr)
                {
                    if(frec[j]==0)
                    {
                        sumaux++;
                        frec[j]=1;
                    }
                }
                while(aux%nr==0)
                {
                    aux/=nr;
                }
            }
            nr++;
            nrmax-=sumaux;
        }
      //  fout<<"dupa "<<i<<" avem "<<nrmax<<endl;
    }
    fout<<nrmax;
}