#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int main()
{
    long long n,i,j,s=0;
    fin>>n;
    s = n;
    for(i=2;i<=n;i++)
    {
        if(n%i == 0)
            s+=n/i;
                else
                   if(n%i !=0) s+=n-1;
    }
    fout<<s+1;
    return 0;
}