#include <iostream>
#include <fstream>
#include <cstring>
#include <string>
#include <climits>
#include <algorithm>
#include <cmath>
using namespace std;

ifstream fin ("fractii.in");
ofstream fout("fractii.out");
#define MAX 1000002

long long int i,s,n,m,a1,t,j,l;


long long int a[MAX];

void inm(long long int* al, long long int* bl, long long int* cl)
{
    cl[0]=al[0]+bl[0]-1;
    for(i=1;i<=al[0];i++)
    {
        for(j=1;j<=bl[0];j++)
        {
            cl[i-1+j]+=al[i]*bl[j];

        }
    }

    for(i=1;i<=cl[0];i++)
    {

        if(cl[i]>9)
        {
            cl[i+1]+=cl[i]/10;
            cl[i]%=10;
        }
    }
    if(cl[i])
        cl[0]++;

}

void transforma(long long int sos, long long int* al)
{
    long long int k=0;

    while(sos)
    {
        al[++k]=sos%10;

        sos/=10;
    }


    al[0]=k;

}

int main()
{

    fin>>n;
    for(i=1;i<=n;i++)
    {
        a[i]=i;
    }
    for(i=2;i<=n;i++)
    {
        if(a[i]==i)
        {
            for(j=i;j<=n;j+=i)
            {
                a[j]/=i;
                a[j]*=i-1;
            }
        }
        s+=a[i];
    }
    fout<<2*s+1;




    return 0;
}