Error when applying long datatype

[iusearch]

I was setting the value of Fortress through nbtutil, the output is like this:

nbtutil --path=r.-2.-1.mca/19.22/Level/Structures/References/Fortress --setvalue -34359738408
/region/r.-2.-1.mca/19.22/Level/Structures/References/Fortress: ERROR (apply)
/region/r.-2.-1.mca/19.22/Level/Structures/References/Fortress: OK
Operation complete.  Nodes succeeded: 1  Nodes failed: 1
WARNING: The runtime version supported by this application is unavailable.
Using default runtime: v4.0.30319

Setting test values are ok. Do I need to specify some option for this operation?

[iusearch]

Any way to just add an entry into the long array?

[iusearch]

I'm such an idiot, seems like there is no method to save an array to the file.