C++ iterator to last element of a set

Question

I have the following code in C++

#include <iostream>
#include <set>

using namespace std;

int main()
{
    set<int> a;
    int n;

    for(int i=0;i<3;i++){
      cin>>n;
      a.insert(n);
    }

    cout << *a.end();
    return 0;
}

Why is it always printing "3" instead of the greatest element in the set? Replacing cout << *a.end(); with cout << *--a.end(); works fine.

Answer 1

To find the last element of a set what we can do is use an iterator that points to last of the of the set and then decrement the iterator to reach the last element as set.end() represent the iterator that points just outside the end of set.

auto it = s.end();
it--;
cout<<(*it)<<endl;

Answer 2

Just use *a.rbegin() which points to the last element in the set