#include <iostream>
#include <fstream>
#include <math.h>

using namespace std;
bool c[499993];
int v[79000],u,x;

int euller(int y)
    {

        int inainte=y;
        int i=3;
        if(y%2==0)
                {inainte=inainte*(2-1)/2;
                while(y%2==0)
                    y=y/2;
                }
        while(y!=1)
            {if(y%i==0)
                {inainte=inainte*(i-1)/i;
                while(y%i==0)
                    y=y/i;
                }
             i=i+2;
            }
        return inainte;
    }


int main()
{
    int i;
    long cate=0;
    ifstream fin("fractii.in");
    ofstream fout("fractii.out");
    fin>>x;
    for(i=1;i<=x;i++)
        cate=cate+euller(i);
    fout<<cate*2-1;
    return 0;
}