#include <iostream>
#include <fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int x,v,sol=0,a[1000005];
int main()
{  int i,j;
    f>>x;
    sol=0;
    for(i=2;i<=x;i++)
       { v=x/i;
          sol+=v*(v-1)/2;
       }
       sol+=x-1;
    sol=x*(x+1)/2-sol;
    sol=2*sol-1;
    g<<sol;
    return 0;
}