How do I insert and erase elements efficiently with std::unordered_set?

// Example of using std::unordered_set in C++
#include <iostream>
#include <unordered_set>

int main() {
    std::unordered_set mySet;
    
    // Inserting elements
    mySet.insert(1);
    mySet.insert(2);
    mySet.insert(3);
    
    std::cout << "Elements after insertions: ";
    for (const auto& elem : mySet) {
        std::cout << elem << " ";
    }
    std::cout << std::endl;

    // Erasing an element
    mySet.erase(2);

    std::cout << "Elements after erasure of 2: ";
    for (const auto& elem : mySet) {
        std::cout << elem << " ";
    }
    std::cout << std::endl;

    return 0;
}