#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: lijinkai
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/