#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using Graph = vector<vector<int>>;
using ull = unsigned long long;
int main() {
  long long N; cin >> N;
  long long ans = 1ll << 60ll;
  vector<int> a;
  if(N == 1) {
    cout << 0 << endl; return 0;
  } 
  while(true) {
    bool fire = true;
    for(int i = 2; i <= sqrt(N); i++) {
      if(N % i == 0){
        N /= i;
        fire =false;
        a.push_back(i);
        break;
      }
    }
    if(fire) break;
  }
  a.push_back(N);
  ans = 0;
  for(int i = 0; i < a.size(); i++) {
    ans += a[i];
  }
  cout << ans << endl;
}