Problem:
Score : 500 points

Problem Statement

Snuke received a positive integer N from Takahashi.
A positive integer m is called a favorite number when the following condition is satisfied:

The quotient and remainder of N divided by m are equal, that is, \lfloor \frac{N}{m} \rfloor = N \bmod m holds.

Find all favorite numbers and print the sum of those.

Constraints

All values in input are integers.

1 \leq N \leq 10^{12}

Input

Input is given from Standard Input in the following format:

N

Output

Print the answer.

Sample Input 1

8

Sample Output 1

10

There are two favorite numbers: 3 and 7. Print the sum of these, 10.

Sample Input 2

1000000000000

Sample Output 2

2499686339916

Watch out for overflow.

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<bits/stdc++.h>
using namespace std;
/*#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
/*template <typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
*/typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll,ll> pl;
typedef pair<int,int> pii;

#define LOCAL 0
#define dbg(x) cout << #x << " is " << x << "\n"
#define gll(x) scanf("%d",&x)
#define gll2(x,y) scanf("%d%d",&x,&y)
#define gll3(x,y,z) scanf("%d%d%d",&x,&y,&z)
#define gllarr(arr,n) f(i,n) gll(arr[i]);
#define sz(x) ((int)x.size())
#define s(x) sort(x.begin(),x.end())
#define all(v) v.begin(),v.end()
#define rs(v) { s(v) ; r(v) ; }
#define r(v) {reverse(all(v));}
#define pb push_back
#define f(i,n) for(int i=0;i<n;i++)
#define fr(i,n) for(int i=n-1;i>=0;i--)
#define rep(i,a,b) for(int i=a;i<=b;i++)
#define repr(i,a,b) for(int i=a;i>=b;i--)

const ll mod = (ll)1e9 + 7;
const ll inf = (ll)1e16;
const ld eps = 1e-12;
const ll N = (int)1e5 + 5;
const ll LOGN = 19;
const ld PI = 3.14159265358979323846;
inline ll mul(ll a, ll b, ll m = mod) { return (ll)(a * b) % m;}
inline ll add(ll a, ll b, ll m = mod) { a += b; if(a >= m) a -= m; if(a < 0) a += m; return a;}
inline ll power(ll a, ll b, ll m = mod) { if(b == 0) return 1; if(b == 1) return (a % m); ll x = power(a, b / 2, m); x = mul(x, x, m); if(b % 2) x = mul(x, a, m); return x;}

void brute(ll n){
    int ans = 0;
    rep(i, 1, n){
        if(n/i == (n % i)) ans += i;
    }
    cout<<"Brute: "<<ans<<endl;
}

ll find(ll n){
    ll ret = 0;
    for(ll i = 1; i * i < n; i++){
        if(n % i) continue;
        ret += (n - i)/i;
    }
    return ret;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    if (LOCAL) {
        freopen("C:\\Users\\Dishant\\Desktop\\Collection-DEV c++\\input.txt", "r", stdin);
        freopen("C:\\Users\\Dishant\\Desktop\\Collection-DEV c++\\output.txt", "w", stdout);
    }
    ll n;
    cin>>n;
    cout<<find(n)<<endl;
    return 0;
}