#include <stdio.h>
#include <iostream>
#include <cstring>
#include <vector>
#include <math.h>
using namespace std;

#define ll long long

#define MaxN 1000

int n;
int d[MaxN];

int main()
{

	scanf("%d",&n);

	for (int i = 2; i <= int( sqrt( double(n) ) ); ++i) {
		while ( n % i == 0 ) {
			d[i]++;
			n /= i;
		}
	}

	ll ret = d[2];
	for (int i = 3; i < n; ++i)
		ret += i*d[i];

	printf("%lld\n",ret);

	return 0;
}