#include <vector>
#include <iostream>
#include <iterator>
#include <initializer_list>
#include <algorithm>
 
class X {
    std::vector<int> data;
public:
    X(std::initializer_list<int> i) : data(i.begin(), i.end()) {}
 
    friend std::ostream &operator<<(std::ostream &os, X const &x) {
        std::copy(x.data.begin(), x.data.end(), std::ostream_iterator<int>(os, "\t"));
        return os;
    }
};
 
int main(){
    X x{1, 2, 3, 4};
 
    std::cout << x;
    return 0;
}
 

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