Ответ:

#include <iostream>

#include <map>

#include <string>

using namespace std;

int main()

{

   map<string, string> students;

   students["Ivanov"] = "Ivan";

   students["Petrov"] = "Petro";

   students["Sidorov"] = "Sidor";

   string surname;

   cout << "Enter surname: ";

   cin >> surname;

   cout << "Name: " << students[surname] << endl;

   return 0;

}

Объяснение: