multiset c++

#include <iostream> 
#include <set> 
#include <iterator> 
  
using namespace std; 
  
int main() 
{ 
    // empty multiset container 
    multiset <int, greater <int> > gquiz1;         
  
    // insert elements in random order 
    gquiz1.insert(40); 
    gquiz1.insert(30); 
    gquiz1.insert(60); 
    gquiz1.insert(20); 
    gquiz1.insert(50); 
    gquiz1.insert(50); // 50 will be added again to the multiset unlike set 
    gquiz1.insert(10); 
  
    // printing multiset gquiz1 
    multiset <int, greater <int> > :: iterator itr; 
    cout << "\nThe multiset gquiz1 is : "; 
    for (itr = gquiz1.begin(); itr != gquiz1.end(); ++itr) 
    { 
        cout << '\t' << *itr; 
    } 
    cout << endl; 
  
    // assigning the elements from gquiz1 to gquiz2 
    multiset <int> gquiz2(gquiz1.begin(), gquiz1.end()); 
  
    // print all elements of the multiset gquiz2 
    cout << "\nThe multiset gquiz2 after assign from gquiz1 is : "; 
    for (itr = gquiz2.begin(); itr != gquiz2.end(); ++itr) 
    { 
        cout << '\t' << *itr; 
    } 
    cout << endl; 
  
    // remove all elements up to element with value 30 in gquiz2 
    cout << "\ngquiz2 after removal of elements less than 30 : "; 
    gquiz2.erase(gquiz2.begin(), gquiz2.find(30)); 
    for (itr = gquiz2.begin(); itr != gquiz2.end(); ++itr) 
    { 
        cout << '\t' << *itr; 
    } 
  
    // remove all elements with value 50 in gquiz2 
    int num; 
    num = gquiz2.erase(50); 
    cout << "\ngquiz2.erase(50) : "; 
    cout << num << " removed \t" ; 
    for (itr = gquiz2.begin(); itr != gquiz2.end(); ++itr) 
    { 
        cout << '\t' << *itr; 
    } 
  
    cout << endl; 
  
    //lower bound and upper bound for multiset gquiz1 
    cout << "gquiz1.lower_bound(40) : " 
         << *gquiz1.lower_bound(40) << endl; 
    cout << "gquiz1.upper_bound(40) : " 
         << *gquiz1.upper_bound(40) << endl; 
  
    //lower bound and upper bound for multiset gquiz2 
    cout << "gquiz2.lower_bound(40) : " 
         << *gquiz2.lower_bound(40) << endl; 
    cout << "gquiz2.upper_bound(40) : " 
         << *gquiz2.upper_bound(40) << endl; 
           
         return 0; 
  
}