#include <set> #include <cstdio> using namespace std; int main() { multiset<int> s = {1, 2, 3}; s.insert(s.begin(), s.end()); //{1, (1), 2, 3} //{1, (1), 1, 2, 3} //{1, 1, (1), 2, 3} for (int x : s) printf("%d " ,x); }