#include<bits/stdc++.h>
using namespace std;

#define int long long

typedef long long ll;
typedef pair<int,int>pint;
typedef vector<int>vint;
typedef vector<pint>vpint;
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define ln <<endl
#define all(v) (v).begin(),(v).end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define reps(i,f,n) for(int i=(f);i<(n);i++)
#define each(it,v) for(__typeof((v).begin()) it=(v).begin();it!=(v).end();it++)
template<class T,class U>void chmin(T &t,U f){if(t>f)t=f;}
template<class T,class U>void chmax(T &t,U f){if(t<f)t=f;}

signed main(){
    int N;cin>>N;
    if(N%2==0)N/=2;

    int sum=0;
    for(int i=1;i*i<=N;i++){
        if(N%i)continue;
        sum+=i;
        if(i*i!=N)sum+=N/i;
    }
    cout<<sum<<endl;
    return 0;
}