#include<iostream>
#include<algorithm>
#include<string>
#include<math.h>
#include<bitset>
#include <vector>
#include<bitset>
#include <iomanip>
#include <map>
#include <set>
#include <stack>
#include <deque>
#include <climits>
#include <queue>
using namespace std;

int main() {
	map<int, int> Prime;
	for (int i = 2; i <= 1000; i++) {
		int D = pow(i, 0.5);
		int count = 0;
		for (int j = 2; j <= D; j++) {
			if (i % j == 0)count++;
		}
		if (count == 0)Prime[i]++;
	}
	int N;
	cin >> N;
	int answer = 0;
	for (int i = 2; i <= N; i++) {
		if (Prime[i] > 0)answer=answer+i;
    }
	cout << answer;
   
}