These are the packages that would be merged, in order:

Calculating dependencies ...

!!! Problem resolving dependencies for =sci-physics/fastjet-3.5.1
 done!
Dependency resolution took 0.83 s (backtrack: 0/20).


!!! The ebuild selected to satisfy "=sci-physics/fastjet-3.5.1" has unmet requirements.
- sci-physics/fastjet-3.5.1::gentoo USE="plugins python -cgal -doc -examples" PYTHON_SINGLE_TARGET="-python3_12 -python3_13"

  The following REQUIRED_USE flag constraints are unsatisfied:
    python? ( exactly-one-of ( python_single_target_python3_12 python_single_target_python3_13 ) )