#include <iostream>

#include <map>

using namespace std;

​

int main() {

  map<string, int> people = { {"John", 32}, {"Adele", 45}, {"Bo", 29} };

​

  // Remove an element by key

  people.erase("John");

  // This will throw an error as John no longer exists

  cout << "John is: " << people.at("John") << "\n";

  return 0;

}

​