long keyword is used in field, method, property, and variable declarations and in cast and
typeof operations as an alias for the .NET Framework structure
System.Int64. That is, it represents a 64-bit signed integer whose value ranges from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.
|Special C# Identifiers (Contextual Keywords)|
|Contextual Keywords (Used in Queries)|