#include<bits/stdc++.h>
using namespace std;
int n,s=0; 
int main(){
cin>>n;
for(int i=2;i*i<=n;i++){
	if(n%i==0) {
		if(i==n/i) s=s+i;
		else s=i+n/i; 
		
		
	}


	
} 
 cout<<s;
	return 0;
}

/**************************************************************
	Problem: 1084
	User: lihean
	Language: C++
	Result: Wrong Answer
****************************************************************/