#include <string>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <numeric>
#include <bitset>
#include <list>
#include <stdexcept>
#include <functional>
#include <utility>
#include <iomanip>
#include <ctime>
#include <valarray>
#include <iostream>
#include <sstream>
#include <fstream>
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
#define MEM(a,b) memset((a),(b),sizeof(a))
const LL INF = 1e9 + 7;
const int N = 2e5 + 10;
vector<int> v;
int flag[N];
void init()
{
	for (int i = 2; i < N; i++)
	{
		if (flag[i]) continue;
		v.push_back(i);
		for (int j = i; j < N; j += i)
			flag[j] = 1;
	}
}
int main()
{
	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);
	LL n;
	cin >> n;
	init();
	LL ans = 0;
	for (auto& x : v)
	{
		LL cur = x;
		while (cur <= n / x)
		{
			cur *= x;
			ans += cur;
		}
	}
	cout << ans << endl;
	return 0;
}