Оставить в коллекции L только первые вхождения одинаковых элементов

#include <algorithm>
#include <iostream>
#include <cstdlib>
#include <vector>
#include <ctime>
#include <list>
#include <set>
#include <map>
using namespace std;
 
template <class T>
void Rand_Vec_list(T &t, int x)
{
    for (int i = 0 ; i<x; i++) t.push_back(rand());
}
 
template <class T>
void Rand_Set(T &t, int x)
{
    for (int i = 0 ; i<x; i++) t.insert(rand());
}
template <class T>
void Show_(T t)
{
    for (auto x: t) cout<<x<<" ";
    cout<<endl;
}
template <class T>
void Rand_Map(T &t,int x)
{
    for (int i = 0; i < x; i++) t[i]=rand();
}
template <class T>
void Show_Map(T &t)
{
    for (auto x: t) cout<<x.second<<" ";
}
 
 
int main() {
 
    srand(time(0));
 
    vector<int> v;
    list<int> l;
    set<int> s;
    multiset<int> ms;
    map<int, int> m;
    int number = 15;
 
    cout<<"vector ";
    unsigned int start_time_vec =  clock();
    for (int i = 0; i < number; i++) v.push_back(rand());
    for_each(v.begin(), v.end(), [&v](int _n)
    {
        cout << _n<< " ";
    });
    unsigned int end_time_vec = clock();
 
    cout<<endl<<"list ";
    unsigned int start_time_list =  clock();
    for (int i = 0; i < number; i++) l.push_back(rand());
    for_each(l.begin(), l.end(), [&l](int _n)
    {
        cout << _n<< " ";
    });
    unsigned int end_time_list = clock();
 
    cout<<endl<<"set ";
    unsigned int start_time_set =  clock();
    for (int i = 0; i < number; i++) s.insert(rand());
    for_each(s.begin(), s.end(), [&s](int _n)
    {
        cout << _n<< " ";
    });
    unsigned int end_time_set = clock();
 
    cout<<endl<<"multiset ";
    unsigned int start_time_mset =  clock();
    for (int i = 0; i < number; i++) ms.insert(rand());
    for_each(ms.begin(), ms.end(), [&ms](int _n)
    {
        cout << _n<< " ";
    });
    unsigned int end_time_mset = clock();
 
    cout<<endl<<"map ";
    unsigned int start_time_map =  clock();
    for (int i = 1; i < number; i++) m[i]=rand();
    for (auto it = m.begin(); it != m.end(); it++) cout << (*it).second<<" ";
    for_each(m.begin(), m.end(), [&m](pair<int,int> n)
    {
       cout<<n.second<<" ";
    });
    unsigned int end_time_map = clock();
 
    cout<<endl<<endl<<"Vector time: "<<end_time_vec-start_time_vec<<endl<<"List time: "<<end_time_list-start_time_list
    <<endl<<"Set time: "<<end_time_set-start_time_set<<endl<<
    "Multiset time: "<<end_time_mset-start_time_mset<<endl<<"Map time: "<<end_time_map-start_time_map;
 
    return 0;
}