partial class Program
{
  static void Output(string title, IEnumerable<string> collection)
  {
    WriteLine(title);
    foreach (string item in collection)
    {
      WriteLine($"  {item}");
    }
  }

  static void OutputPQ<TElement, TPriority>(string title,
    IEnumerable<(TElement Element, TPriority Priority)> collection)
  {
    WriteLine(title);
    foreach ((TElement, TPriority) item in collection)
    {
      WriteLine($"  {item.Item1}: {item.Item2}");
    }
  }
}