#include <iostream>
#include <string>
#include <set>
using namespace std;
 
class Feat 
{
public:
	Feat(int a){ _a = a;}
	int GetA() {return _a;}
	int _a;
};
struct lexical_compare {
	bool operator() (Feat a, Feat b) const {
		return a.GetA() < b.GetA();
	}
};
 
int main() {
    set<Feat, lexical_compare> s;
 
    s.insert(Feat(1));
    s.insert(Feat(10100));
    s.insert(Feat(18));
    s.insert(Feat(100));
 
    for (Feat x : s)
        cout << x.GetA() << ' ';
 
    return 0;
}

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