Set and Map Templates in C++

#include <iostream>
#include <string>
#include <set>

using namespace std;
//we will see a lot of set algorithms in this example

int main(){
    // first we need an empty set container
    set <int, greater <int> > setOne;

    // now we can insert elements in random order
    // however, the numbers are unique
    setOne.insert(55);
    setOne.insert(89);
    setOne.insert(1);
    setOne.insert(41);
    setOne.insert(74);
    setOne.insert(23);
    setOne.insert(32);

    // to print set one, we need an iterator
    set <int, greater <int> > :: iterator itr;
    cout << "The iterator automatically orders the arrangement." << endl;
    cout << "Set one is now in descending order : ";
    for (itr = setOne.begin(); itr != setOne.end(); ++itr){
        cout << *itr << ", ";
    }
    cout << endl;

    // we can use a special algorithm to reverse the order
    // to do that, we need to assign the values of set one
    // to another set called set two
    set <int> setTwo(setOne.begin(), setOne.end());
    cout << endl;

    // now we can display the value of set two
    cout << "Set two is now in ascending order : ";
    for (itr = setTwo.begin(); itr != setTwo.end(); ++itr){
        cout << *itr << ", ";
    }
    cout << endl;

    // we can remove elements below 41 from set two
    cout << "Removing values below 41 from set two: " << endl;
    cout << "Now set two will start from 41: " << endl;
    cout << "Now set two looks like this: " << endl;
    setTwo.erase(setTwo.begin(), setTwo.find(41));
    for (itr = setTwo.begin(); itr != setTwo.end(); ++itr){
        cout << *itr << ", ";
    }
    cout << endl;

    // we can remove any particular element whose value is 41 in set two
    setTwo.erase (41);
    cout << "Erasing 41 from set two" << endl;
    cout << "Now set two will start from the value after 41 : " << endl;
    cout << "Now set two looks like this: " << endl;
    for (itr = setTwo.begin(); itr != setTwo.end(); ++itr){
        cout << *itr << ", ";
    }

    cout << endl;
    cout << "None of the algorithms applied on set two have affected set one : " << endl;
    cout << "Set one remains the same; it looks like this: " << endl;
    for (itr = setOne.begin(); itr != setOne.end(); ++itr){
            cout << *itr << ", ";
    }
    cout << endl;
    return 0;
}