#include <cstdio>
using namespace std;
int n,p,q,r,nr,a,b,d,k,s,e;
int main()
{FILE*f=fopen("fractii.in","r");
FILE*g=fopen("fractii.out","w");
fscanf(f,"%d",&n);
nr=n;
for(p=2; p<=n; p++){
	a=p;
	d=1;
	e=0;
	k=1;
	s=0;
	while(a!=1){
		e=0;
		d=d+1;
		while(a%d==0){
			e=e+1;
			a=a/d;
		}
		k=k*(e+1);
		s=s+k;
	}
	nr=nr+s;
}
	
	
	fprintf(g,"%d",nr-1);
}