srm741div2med

srm741div2med.cpp

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

typedef long long ll;

template<typename T>
void out(T x) { cout << x << endl; exit(0); }


const int maxn=(int)4e5+5;

class SimpleMathProblemDiv2 {
public:
  long long calculate(int X);
};

ll g(int n, int p) {
  if (n%p) return 0;
  ll ans = 1;
  while (ans*p <= n) ans*=p;
  return ans;
}




ll f(int n) {
  ll ans = 0;
  int _n = n;
  for (int p=2; p*p <=n; p++) {
    if (n%p == 0) {
      while (n%p == 0) n = n/p;
      ans += g(_n, p);
    }
  }
  if (n > 1) ans += g(_n, n);
  return ans;   
}

long long SimpleMathProblemDiv2::calculate(int x) {
  if (x==1) return 0;
  ll ans = 0;
  for (int n=1; n<=x; n++) {
    ans+=f(n);
  }
  return ans;
}

int main() {
  ios_base::sync_with_stdio(false); cin.tie(0);  cout.tie(0);
  //cout << fixed << setprecision(6);
  SimpleMathProblemDiv2 d;
  int x; cin>>x;
  cout<<d.calculate(x)<<endl;

  return 0;
}