https://learn.microsoft.com/pt-pt/dotnet/api/system.linq.enumerable.longcount?view=netframework-4.8.1&viewFallbackFrom=windowsdesktop-9.0
Enumerable.LongCount Method (System.Linq) | Microsoft Learn
Returns an Int64 that represents the number of elements in a sequence.
enumerablelongcountmethodsystemlinq