public void GetHashCodeTest()
{
int h1 = p1.GetHashCode();
int h2 = p2.GetHashCode();
int h3 = p3.GetHashCode();
int h4 = p4.GetHashCode();
Console.WriteLine($"h1 = {h1}");
Console.WriteLine($"h2 = {h2}");
Console.WriteLine($"h3 = {h3}");
Console.WriteLine($"h4 = {h4}");
}