#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n,s=0;
	cin>>n;
	for(int i=2;i<=sqrt(n);i++)
	{
		if(n%i==0)
		{
			s+=i;
			s+=n-i;
		}
	}
	cout<<s;
	return 0;
}
/**************************************************************
	Problem: 1084
	User: wangyuxin
	Language: C++
	Result: Wrong Answer
****************************************************************/