My strategy

Hi at all, I’m new. When I complete a puzzle I at first fold the RNA using only GC, then, expecially in the puzzle with a GC limit I subsistute it with AU and, at the end with GU.
I tried to substitute GC with GU, but in some structures don’t work; you can’t subsitute all GC and GU and at the end you are stuck…
You can do it when the structure is very stable and you have to create more GU bonds possible.