#include<bits/stdc++.h>
using namespace std;
int n,s,i;
int main(){
	cin>>n;
	if(n%2==1){
		i=2;
		while(i<=n){
			s=s+i;
			i+=2;
		}
	}else{
		i=1;
		while(i<=n){
			if(n%i==0) s=s+i;
			i++;
		}
	}
	cout<<s;
	return 0;
}
/**************************************************************
	Problem: 1060
	User: zhangziang
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/