#include <stdio.h>
#include <stdlib.h>
#include <math.h>


int main(int argc, char *argv[])
{
    long n = 0;
    long nr = 0;
    long i = 0;
    FILE * f = fopen("fractii.in", "r");
    fscanf(f, "%ld", &n);
    fclose(f);
    nr = 2 * n - 1;
    for ( i = 2; i <=  (n / 2) ; i++)
    {
        nr = nr + 2 * (n - (n / i));
    }
    if ( n % 2 == 1 )  nr = nr + (n - (n / i));
    f = fopen("fractii.out", "w");
    fprintf(f, "%ld", nr);
    fclose(f);
    return 0;
}