Which lines can be inserted in the specified place

Which lines can be inserted in the specified place so that “12345” appears on the screen? Each option implies that only it is inserted.

#include <iostream>
#include <algorithm>
#include <iterator>
#include <vector>

int main()
{
    std::vector<int> v = {1, 4, 2, 5, 3, 2, 3};
    // <<< insert here >>>
}

std::sort(v.begin(), v.end());
std::unique_copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout));

std::sort(v.begin(), v.end());
std::vector<int>::iterator it = std::unique(v.begin(), v.end());
std::copy(v.begin(), it, std::ostream_iterator<int>(std::cout));

std::vector<int>::iterator it = std::unique(v.begin(), v.end());
std::sort(v.begin(), it);
std::copy(v.begin(), it, std::ostream_iterator<int>(std::cout));

std::unique_copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout));

std::vector<int>::iterator it = std::unique(v.begin(), v.end());
std::sort(v.begin(), it);
std::unique_copy(v.begin(), it, std::ostream_iterator<int>(std::cout));

Explanation

The std::unique function compares two neighboring elements using the == operator, returns an iterator to the element that follows the last undeleted (not moved to the end). In our case, if we apply the algorithm without preliminary sorting, then an iterator equal to the end will be returned.