#include <iostream>
#include <fstream>

using namespace std;

int main()
{
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    unsigned int Q,nr,y,j,z;
    f>>nr;
    //nr = 9;
    Q = nr;
    nr = (nr-1)*2+1;
    unsigned int*x;
    x = new unsigned int[nr];
    for(int i = 1;i<=nr;i++)
         x[i]=1;

    for(unsigned int i=2;i<=Q;i++){
        nr+=(Q-i)*2;
        y=0;
        z=1;
        if(x[i]==0){
            continue;
        }
        else{
        j =i+i;
        while(j<=Q){

            y+=z;
            z++;
            x[j]=0;
            j=j+i;
        }

        nr-=y*2;
    }
    }
    //cout<<nr;
    //cin>>nr;
    g<<nr;
    return 0;
}