Shared Pointer in C++

#include <iostream>
#include <memory>
using namespace std;

int main()
{
    shared_ptr<int> ptr1 = make_shared<int>(900);
    shared_ptr<int> ptr2 = ptr1;
    shared_ptr<int> ptr3 = ptr1;
    cout << "Shared pointer 1 : " << *ptr1 << endl;
    cout << "Shared pointer 2 : " << *ptr2 << endl;
    cout << "Shared pointer 3 : " << *ptr3 << endl;

    return 0;
}