#include<iostream>
#include <bits/stdc++.h>
using namespace std;
#include<deque>
#define rep(i,a,b) for(LL i = a;i<b; i++)
#define rrep(i,a,b) for(LL i = a;i>b; i--)
#define tobirep(i,a,b,c) for(LL i = a;i<b; i+=c)
#define tobirrep(i,a,b,c) for(LL i = a;i>b; i-=c)
#define INF  2000000000
#define ooki 9,223,372,036,854,775,807
#define tii -9,223,372,036,854,775,808
typedef long long LL;
LL f(LL x){
  rep(i,2,sqrt(x)+1){
    if(x%i==0&&i!=x){return 0;}
  }
  return 1;
}
int main(){
 LL n,sum=0;
  cin >> n;
  rep(i,2,n+1){
    if(f(i)){sum+=i;}
  }
  cout << sum << endl;       
}