#include <iostream>
#include <list>
#include <algorithm>
 
int main() {
    const std::list<char> in { 'a', 'b', 'c', 'd' };
    std::list<char> out { '1', '2', '3', '4' };
    std::copy(begin(in), end(in), std::front_inserter(out));
    for (auto c: out) std::cout << c;
    std::cout << std::endl;
    
    out = { '1', '2', '3', '4' };
    const auto it = std::find(begin(out), end(out), '3');
    std::copy(begin(in), end(in), std::inserter(out, it));
    for (auto c: out) std::cout << c;
    std::cout << std::endl;
    
    out = { '1', '2', '3', '4' };
    std::copy(begin(in), end(in), std::back_inserter(out));
    for (auto c: out) std::cout << c;
    std::cout << std::endl;
}