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

int main(void)
{
    int *v,i,j,x,N;
    long long nr=0;

    FILE *f=fopen("fractii.in","rt");
    FILE *g=fopen("fractii.out","wt");

    fscanf(f,"%d",&N);
    v=malloc(N*sizeof(*v));

    for(i=0;i<N;i++)
        v[i]=i+1;

    for(i=2;i<=N/2;i++)
    {
        for(j=i-1;j<N;j+=i)
        {
            if(v[j]%i==0)
            {
                nr=nr+v[j]/i;
            }
        }

    }
    printf("%d",nr+N);
    fprintf(g,"%d",nr+N);
    return 0;
}