#define _USE_MATH_DEFINES
#define _CRT_SECURE_NO_WARNINGS

#include <iostream>
#include <string>
#include <sstream>
#include <iomanip>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <stack>
#include <queue>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <bitset>
#include <utility>
#include <numeric>
#include <iterator>

using namespace std;

using ll = long long;
using ull = unsigned long long;

const ll inf = 1ll << 60;
const ll mod = (ll)1e9 + 7;

#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()

#define print(s) cout << s;
#define println(s) cout << s << endl;
#define printd(s, f) cout << fixed << setprecision(f) << s << endl;

// 素数かどうかの判定
template<typename T> bool is_prime(T n)
{
	if (n == 2)
	{
		return true;
	}
	else if ((n == 1) || (n % 2 == 0))
	{
		return false;
	}

	for (T i = 3; i * i <= n; i += 2)
	{
		if (n % i == 0)
		{
			return false;
		}
	}

	return true;
}

int main()
{
	ll n;
	cin >> n;

	ull sum = 0;
	for (ll i = 0; i <= n; i++)
	{
		if (is_prime(i))
		{
			sum += i;
		}
	}

	println(sum);
}