#include <cstdio>
#include <vector>
#include <map>
#include <algorithm>
#include <cmath>
#include <iostream>
#include <string>

#define rep(i,N) for(int (i)=0;(i)<(N);(i)++)
#define MOD 1000000007

using namespace std;

int powmod(int a, int b, int p) {
	if (b == 0)return 1;
	else if (b % 2 == 0)return (powmod(a*a, b / 2, p) % p);
	else return (powmod(a, b - 1, p)*a%p);
}

int factorialmod(int a, int p) {
	if (!a)return 1;
	else return a * factorialmod(a - 1, p) % p;
}

int main(){
	int N,ans = 0;
	scanf("%d", &N);
	for (int i = 1; i < N+1; i++) {
		int count = 0;
		for (int j = 1; j < i+1; j++) {
			if (i%j == 0)count++;
		}
		if (count == 2)ans += i;
	}
	printf("%d", ans);
	return 0;
}