#include <bits/stdc++.h>
using namespace std;

int cum_primes(int N){
    // returns a sum of prime numbers up to N (including N).
    if (N == 1) return 0;
    if (N == 2) return 2;
    if (N <= 4) return 5;
    vector<bool> isPrime(N + 1, true);
    for (int p = 5, d = 2; p * p <= N; p += d, d = 6 - d){
        if (isPrime[p]){
            for (int q = p * p, delta = d; q <= N; q += delta * p, delta = 6 - delta){
                isPrime[q] = false;
            }
        }
    }
    int ans = 5;
    for (int p = 5, d = 2; p <= N; p += d, d = 6 - d){
        if (isPrime[p]) ans += p;
    }
    return ans;
}


int main() {
    int N;
    cin >> N;
    cout << cum_primes(N) << endl;
    return 0;
}