#include<iostream>
#include<fstream>
using namespace std;
int main()
{
    int n,i,j,s=0,a[100];
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    f>>n;
    for(i=2;i<=n;i++) a[i]=i-1;
    for(i=2;i<=n;i++)
    {
        s=s+a[i];
        for(j=i+i;j<=n;j=j+i) a[j]=a[j]-(j-i)/i;
    }
    g<<2*s+1;
    f.close();
    g.close();
    return 0;}