#include <stdio.h>
#include <algorithm>
#include <iostream>
#include <string>
#include <vector>
#include <functional>
#include <map>
#include <iomanip>
#include <math.h> 
#include <stack>
#include <queue>
#include <bitset>
#include <cstdlib>
#include <tuple>
#include <cctype>
#include <ctype.h>
#include <set>
#include <sstream>

using namespace std;



int main() {
	int i, j, k;
	int n;

	cin >> n;

	long sum = 0;

	if (n == 1) {
		cout << 0 << endl;
		return 0;
	}
	else if (n == 2) {
		cout << 2 << endl;
		return 0;
	}
	else if (n == 3) {
		cout << 5 << endl;
		return 0;
	}

	if (n >= 4) sum += 5;


	for (i = 4; i <= n; i++) {
		bool flag = false;

		for (j = 2; j < i; j++) {
			//if (j == 2 || j == 3)continue;
			if (i%j == 0){
				flag = true;
				break;
			}
		}
		flag ? 0 : sum += i;

	}

	cout << sum << endl;




	getchar();
	getchar();
	return 0;
}