// Staan er (compile) fouten in dit programma? Indien ja: corrigeer.

#include <iostream>
#include <sstream>
#include <string>
#include <set>

template<typename T> 
std::string
tostring(const T& t) {
std::ostringstream oss;
oss << t;
return oss.str();
}

class A {
public:
  A(int a=3): a_(a) {}
  std::string str() { return tostring(a_); }
private:
  int a_;
};

int
main(int,char**) {
std::set<A>  as;
for (size_t i=0; i<10; ++i) 
  as.insert(A(i));
  
for (std::set<A>::iterator i=as.begin(); i!=as.end(); ++i)
  std::cout << i->str() << std::endl;
}