text: #include <iostream>
  #include <list>
  #include<algorithm>
  
  int main(){
    std::list<int> list1{15, 2, 18, 19, 4, 15, 1, 3, 18, 5, 
                        4, 7, 17, 9, 16, 8, 6, 6, 17, 1, 2};
  
    list1.sort();
    for (auto l: list1) std::cout << l << " ";
       // 1 1 2 2 3 4 4 5 6 6 7 8 9 15 15 16 17 17 18 18 19 
    std::cout<<std::endl;
    
    list1.unique();
    for (auto l: list1) std::cout << l << " ";
       // 1 2 3 4 5 6 7 8 9 15 16 17 18 19
    std::cout<<std::endl;
    
    std::list<int> list2{10, 11, 12, 13, 14};
  
    
    list1.splice(std::find(list1.begin(), list1.end(), 15), list2);
    for (auto l: list1) std::cout << l << " ";
       // 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
  
    return 0;
  }