#include <iostream>
using namespace std;
int SumDel(int a) {
int s = 0;
for (int i = 1; i <= a / 2; i++) {
if (a % i == 0) {
s += i;
}
}
return s;
}
int main() {
int s;
cin >> s;
cout << SumDel(s);
return 0;
}
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