#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 = n - (n / 2) * (n / 2) + n;
    for (i = 3; i <= n ; i = i + 2)
       {
       nr = nr - (n / i) * ((n / i) - 1) - 1 + 2 * n;        
       }
    if ( n % 2 == 1 ) nr = nr - n;
    f = fopen("fractii.out", "w");
    fprintf(f, "%ld", nr);
    fclose(f);
    return 0;
}