#include<stdio.h>
int main(){
FILE *f=fopen("fractii.in","r");

long int n,k,i;

fscanf(f,"%ld",&n);


k=n;
for(i=2;i<=n;i++){

k=k+n/i*(i-1)+(n%i);
}

FILE *g=fopen("fractii.out","w");
fprintf(g,"%ld",k);

fclose(f);
fclose(g);
return 0;
}