#include <iostream>
#include <map>
#include <string>
using namespace std;

// Add a number, name pair to the phonebook using a map.
void add(map<int, string>& phonebook, int number, const string &name) {
    map<int, string>::iterator it = phonebook.find(number);
    if (it != phonebook.end()) {
        it->second = name;
    } else {
        phonebook.insert(pair<int, string>(number, name));
    }
}

// Given a phone number, determine who is calling.
void identify(const map<int, string>& phonebook, int number) {
    map<int, string>::const_iterator it = phonebook.find(number);
    if (it == phonebook.end())
        cout << "unknown caller!" << endl;
    else
        cout << it->second << " is calling!" << endl;
}

int main() {
    // Init
    map<int, string> phonebook;

    // Add
    add(phonebook, 1111, "fred");
    add(phonebook, 2222, "sally");
    add(phonebook, 3333, "george");
    add(phonebook, 1234567, "alice");
    add(phonebook, 7654321, "bob");

    // Test
    identify(phonebook, 2222);
    identify(phonebook, 4444);
    identify(phonebook, 1234567);
    
    return 0;
}