#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
#define rep(i,l,r) for(ll i=(l);i<(r);i++)
#define INF (ll)1e18
struct aaa{aaa(){cin.tie(0); ios::sync_with_stdio(0); cout<<fixed<<setprecision(10);};}aaaaaaa;
inline void in() {}
template <class Head, class... Tail>
inline void in(Head&& head,Tail&&... tail){
    cin>>head;
    in(move(tail)...);
}
template <class T>
inline void out(T t) {
    cout<<t<<'\n';
}
template <class Head, class... Tail>
inline void out(Head head,Tail... tail){
    cout<<head<<' ';
    out(move(tail)...);
}

int main(){
    int p[]={2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,101,103,107,109,113,127,131,137,139,149,151,157,163,167,173,179,181,191,193,197,199,211,223,227,229,233,239,241,251,257,263,269,271,277,281,283,293,307,311,313,317,331,337,347,349,353,359,367,373,379,383,389,397,401,409,419,421,431,433,439,443,449,457,461,463,467,479,487,491,499,503,509,521,523,541,547,557,563,569,571,577,587,593,599,601,607,613,617,619,631,641,643,647,653,659,661,673,677,683,691,701,709,719,727,733,739,743,751,757,761,769,773,787,797,809,811,821,823,827,829,839,853,857,859,863,877,881,883,887,907,911,919,929,937,941,947,953,967,971,977,983,991,997,1000000};
    int n;
    in(n);
    ll ans=0;
    for(ll i=0;p[i]<=n;i++)ans+=p[i];
    out(ans);
}