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