#define _USE_MATH_DEFINES
#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<string>
#include<iostream>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include<stack>
#include<queue>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include <sstream>
#include<iomanip>
#include <ctype.h>
#include <fstream>
#include <cassert>
//#include <bits/stdc++.h>
using namespace std;

//#include<bits/stdc++.h>

bool f[1002];
	
int main() {

	for (int i = 3; i <= 1000; i+=2) {
		f[i] = 1;
		for (int j = 3; j*j <= i; j += 2) {
			if (i%j == 0) {
				f[i] = 0; break;
			}
			}

	}
	f[2] = 1;
	int n;
	cin >> n;
	int r = 0;
	for (int i = 2; i <= n; i++)if (f[i])r += i;
	cout << r << endl;
	
	return 0;
}