A const field requires a value to be provided

MSBuild version 17.9.4+90725d08d for .NET
  Determining projects to restore...
  Restored /home/codegrade/student/Files/Files.csproj (in 146 ms).
/home/codegrade/student/Files/Knight.cs(6,26): error CS0145: A const field requires a value to be provided [/home/codegrade/student/Files/Files.csproj]

Build FAILED.
    0 Warning(s)
    1 Error(s)

Time Elapsed 00:00:01.62