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

int main() {
	map<string, set<string>> data;
    data["Key1"].emplace("hello");
    data["Key1"].emplace("world");
    data["Key1"].emplace("test");
    data["Key2"].emplace("Ciao");
    data["Key2"].emplace("Mondo");

    for (const auto& x : data) {
        cout << x.first << ": ";
        bool first = true;
        for (const auto& s : x.second) {
            if (!first) {
                cout << ", ";
            } else {
                first = false;
            }
            cout << s;
        }
        
        cout << endl;
    }


	return 0;
}