#include <iostream>     // std::cout
#include <algorithm>    // std::set_difference, std::sort
#include <iterator>     // std::back_inserter
#include <vector>       // std::vector
 
int main()
{
    std::vector< int > a = { 1, 3, 5 };
    std::vector< int > b = { 1, 2, 4, 5 };
 
    std::sort( a.begin(), a.end() );
    std::sort( b.begin(), b.end() );
 
    std::vector< int > result;
    std::set_difference( a.begin(), a.end(), b.begin(), b.end(), std::back_inserter(result) );
    std::set_difference( b.begin(), b.end(), a.begin(), a.end(), std::back_inserter(result) );
 
    for ( int x : result )
        std::cout << x << "\n";
 
    return 0;
}

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