#include<bits/stdc++.h >
using namespace std;
int s, a[1005], dp[1005];
int f(int x) {
	int ans = 0;
	for (int i = 1; i < x; i++)
		if (x % i == 0)
			ans += i;
	return ans;
}
int main() {
	cin >> s;
	for (int i = 1; i <= s; i++)
		a[i] = f(i);
	for (int i = 1; i <= s; i++) {

		for (int j = s; j >= i; j--) {
			dp[j] = max(dp[j], dp[j - i] + a[i]);
		}
	}
	cout << dp[s];
	return 0;
}