#include<iostream>
#include<cstring>
#include<vector>
#include<algorithm>
#include<cmath>
#include<queue> 
#define ll long long
#define rev(x) reverse(x.begin(),x.end())
using namespace std;
int main(){
    freopen("hs.in","r",stdin);
    freopen("hs.out","w",stdout);
    
    ll x;cin>>x;
    ll p=0,ans=0x3f3f3f3f;
    
    for(ll xp=x;xp<2*x;xp++){
    	ll xpo=xp;
	    for(ll i=2;i<=xpo;i++){
	    	while(xpo%i==0) xpo/=i,p+=i;
		}
		ans=min(ans,p);
	}
	cout<<ans;
    
    
    
    return 0;
}