#include "bits/stdc++.h"

#define REP(i, n, N) for(ll i=(n); i<(N); i++)
#define RREP(i, n, N) for(ll i=(N-1); i>=n; i--)
#define CK(n, a, b) ((a)<=(n)&&(n)<(b))
#define ALL(v) (v).begin(),(v).end()
#define MCP(a, b) memcpy(b,a,sizeof(b))
#define p(s) cout<<(s)<<endl
#define p2(a, b) cout<<(a)<<" "<<(b)<<endl
#define v2(T) vector<vector<T>>
typedef long long ll;
using namespace std;
const ll mod = 1e9 + 7;
const ll inf = 1e18;

vector<int> hurui_v(int n) {
    vector<int> v;
    bool *isPrime_v;
    isPrime_v = new bool[n + 1]; // 処理用のメモリ確保

    // 初期化
    isPrime_v[0] = isPrime_v[1] = false;
    for (int i = 2; i < n + 1; i++) isPrime_v[i] = true;

    // isPrime[0~n]で素数のものだけtrueにする
    for (int i = 2; i*i <= n; i++) {
        for (int j = i * 2; j < n + 1; j += i) {
            isPrime_v[j] = false;
        }
    }

    // 素数のみ追加
    for (int i = 0; i < n + 1; i++) {
        if (isPrime_v[i]) v.push_back(i);
    }

    delete[] isPrime_v; //メモリ解放
    return v;
}

int main() {
    int N;
    cin>>N;
    int ans=0;
    auto vp = hurui_v(N);
    for(auto v:vp){
        ans+=v;
    }

    p(ans);
    return 0;
}