C++STLトレーナー(multisetの使用)

#include   
#include   
using namespace std;  
  
int main()  
{  
    ///1.      
    multiset num;  
    multiset::iterator iter,beg,end;  
    cout << num.max_size() << endl;///multiset      
    cout << endl;  
  
    ///2.       
    for (int i = 0; i < 10; i++)  
        num.insert(i);  
    cout << num.size() << endl;  
    cout << endl;  
  
    ///3.     
    for (iter = num.begin(); iter != num.end(); iter++)  
        cout << *iter << " " ;  
    cout << endl;  
    cout << endl;  
  
    ///4.     
  
    iter = num.find(1);  
    if (iter != num.end())  
        cout << *iter << endl;  
    else  
        cout << -1 << endl;  
  
    iter = num.find(99);  
    if (iter != num.end())  
        cout << *iter << endl;  
    else  
        cout << -1 << endl;  
    cout << endl;  
  
    beg=num.lower_bound(2);  
    end=num.upper_bound(7);  
    for (; beg != end; beg++)  
        cout << *beg << " " ;  
    cout << endl;  
  
    ///5.     
    iter = num.find(1);  
    num.erase(iter);  
    cout << num.size() << endl;  
    for (iter = num.begin(); iter != num.end(); iter++)  
        cout << *iter << " " ;  
    cout << endl;  
    cout << endl;  
  
    ///6.        
    if (!num.empty())  
        num.clear();  
}